[jaegermcp] Enforce config-driven limits in MCP handlers by rite7sh · Pull Request #8194 · jaegertracing/jaeger

rite7sh · 2026-03-18T10:58:30Z

Which problem is this PR solving?

Fixes #8193

This PR addresses an issue where configuration-defined limits in the Jaeger MCP extension were not being enforced.

Specifically:

MaxSearchResults was defined but not used in search_traces handler (hardcoded limits were used instead)
MaxSpanDetailsPerRequest was defined but not enforced in get_span_details handler

This resulted in potential unbounded payload sizes and inconsistency between configuration and runtime behavior.

Description of the changes

Pass MaxSearchResults and MaxSpanDetailsPerRequest from server.go into MCP handlers
Replace hardcoded limits in search_traces with config-driven limits
Add validation in get_span_details to enforce MaxSpanDetailsPerRequest
Update handler constructors to accept limit parameters
Update all call sites and tests to match new constructor signatures
Add a unit test to verify span limit enforcement behavior

How was this change tested?

Ran full test suite using make test
Updated existing unit tests to reflect constructor changes
Added a new test (TestGetSpanDetailsHandler_ExceedsLimit) to verify:
- Error is returned when span request exceeds configured limit
- Error message contains correct limit information
Verified no regressions in existing MCP handler tests

Checklist

I have read https://github.com/jaegertracing/jaeger/blob/main/CONTRIBUTING_GUIDELINES.md
I have signed all commits
I have added unit tests for the new functionality
I have run lint and test steps successfully: make lint test

AI Usage in this PR (choose one)

None: No AI tools were used in creating this PR
Light: AI provided minor assistance (formatting, simple suggestions)
Moderate: AI helped with code generation or debugging specific parts
Heavy: AI generated most or all of the code changes

Copilot

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Signed-off-by: Ritesh Tripathi <ritesh6263tripathi@gmail.com>

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Pull request overview

Enforces Jaeger MCP extension configuration limits at runtime by threading configured maximums into the MCP tool handlers and applying them during request handling, preventing unbounded payload sizes and keeping behavior consistent with jaeger_mcp config.

Changes:

Pass MaxSearchResults and MaxSpanDetailsPerRequest from server.go into the search_traces and get_span_details handlers.
Replace hardcoded search_traces depth/result caps with config-driven limits.
Add span count validation in get_span_details and update/add unit tests for the new behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
cmd/jaeger/internal/extension/jaegermcp/server.go	Wires config limits into handler constructors when registering MCP tools.
cmd/jaeger/internal/extension/jaegermcp/internal/handlers/search_traces.go	Removes hardcoded caps; clamps `search_depth` using injected configured maximum.
cmd/jaeger/internal/extension/jaegermcp/internal/handlers/get_span_details.go	Enforces max spans per request via injected configured maximum.
cmd/jaeger/internal/extension/jaegermcp/internal/handlers/search_traces_test.go	Updates tests to include the new handler limit field/constructor signature.
cmd/jaeger/internal/extension/jaegermcp/internal/handlers/get_span_details_test.go	Updates tests for new signature and adds coverage for exceeding the span limit.

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- Remove hardcoded 'max: 100' reference from SearchDepth field documentation - Clarify that maximum is controlled by server configuration (MaxSearchResults) - Align documentation with config-driven limit enforcement implementation Signed-off-by: Ritesh Tripathi <ritesh6263tripathi@gmail.com>

Signed-off-by: Ritesh Tripathi <ritesh6263tripathi@gmail.com>

Copilot

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

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Pull request overview

This PR fixes Jaeger MCP limit enforcement by wiring configuration-defined limits into MCP tool handlers and applying those limits at runtime to prevent unexpectedly large responses.

Changes:

Pass MaxSearchResults and MaxSpanDetailsPerRequest from server.go into the search_traces and get_span_details handlers.
Replace search_traces hardcoded caps with a handler-configured maximum.
Enforce MaxSpanDetailsPerRequest in get_span_details, including a new unit test for the over-limit case.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
cmd/jaeger/internal/extension/jaegermcp/server.go	Passes configured limits into handler constructors during tool registration.
cmd/jaeger/internal/extension/jaegermcp/server_test.go	Updates server tests’ config setup to include required limit fields.
cmd/jaeger/internal/extension/jaegermcp/internal/types/search_traces.go	Updates schema/docs to reflect config-controlled maximum for `search_depth`.
cmd/jaeger/internal/extension/jaegermcp/internal/handlers/search_traces.go	Adds `maxResults` to handler and clamps `SearchDepth` using the configured limit.
cmd/jaeger/internal/extension/jaegermcp/internal/handlers/search_traces_test.go	Updates tests for the new handler struct/constructor signature.
cmd/jaeger/internal/extension/jaegermcp/internal/handlers/get_span_details.go	Adds per-request span ID count enforcement based on configured limit.
cmd/jaeger/internal/extension/jaegermcp/internal/handlers/get_span_details_test.go	Updates tests for new constructor signature and adds an exceeds-limit test.

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Signed-off-by: Ritesh Tripathi <ritesh6263tripathi@gmail.com>

codecov · 2026-03-18T18:52:15Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.63%. Comparing base (af51e32) to head (b00175a).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8194   +/-   ##
=======================================
  Coverage   95.62%   95.63%           
=======================================
  Files         318      318           
  Lines       16771    16780    +9     
=======================================
+ Hits        16038    16047    +9     
  Misses        578      578           
  Partials      155      155

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yurishkuro · 2026-03-18T19:12:14Z

Thanks!

) ## Which problem is this PR solving? When an agent calls `search_traces`, the response includes `service_count` (an integer) but not the actual service names. The agent knows a trace spans 5 services but has no idea which ones. To find out, it must call `get_trace_topology` or `get_span_details` for every trace individually, which defeats the purpose of a lightweight summary endpoint. The data is already computed internally. `buildTraceSummary` builds a `services` map to derive `service_count`, then discards the map keys. This has been the case since the function was introduced in #7858, where the map was built but only `len(services)` was surfaced. Subsequent changes (#7859, #7863, #7916, #8194) restructured the types and renamed fields but never revisited the service data gap. ## Short description of the changes - Added `Services []string` to `TraceSummary`, populated from the existing `services` map - Sorted alphabetically via `slices.Sort` for deterministic output across calls - Added multi-service test with three services in non-alphabetical order, unique span IDs, and proper parent-child relationships to verify sort correctness - Updated existing summary tests to assert on the new field - `ServiceCount` preserved for backward compatibility ## Use case An agent investigating a latency spike searches for slow traces. The summary now returns: ```json { "service_count": 3, "services": ["api-gateway", "payment", "user-service"] } ``` The agent can immediately see that the payment service is involved and drill into that trace, instead of blindly fetching topology for every result. ## How was this change tested? - `go test ./cmd/jaeger/internal/extension/jaegermcp/...` - all passing - `make lint` - 0 issues - `make fmt` - clean - `make test` - 3053 tests passing ## Checklist - [x] I have read https://github.com/jaegertracing/jaeger/blob/main/CONTRIBUTING_GUIDELINES.md - [x] I have signed all commits - [x] I have added unit tests for the new functionality - [x] I have run lint and test steps successfully: `make lint test` ## AI Usage in this PR (choose one) - [x] **Light**: AI provided minor assistance (formatting, simple suggestions) Signed-off-by: Roshan Singh <roshansingh7890@gmail.com> Signed-off-by: Roshan <rosh.s568@gmail.com>

rite7sh requested a review from a team as a code owner March 18, 2026 10:58

Copilot AI review requested due to automatic review settings March 18, 2026 10:58

dosubot Bot added the enhancement label Mar 18, 2026

Copilot started reviewing on behalf of rite7sh March 18, 2026 10:59 View session

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jaegermcp: enforce config-driven limits in MCP handlers

825da4a

Signed-off-by: Ritesh Tripathi <ritesh6263tripathi@gmail.com>

rite7sh force-pushed the fix/mcp-config-limits branch from 2d3be50 to 825da4a Compare March 18, 2026 11:05

jkowall requested a review from Copilot March 18, 2026 12:34

jkowall added the changelog:bugfix-or-minor-feature label Mar 18, 2026

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Comment thread cmd/jaeger/internal/extension/jaegermcp/internal/handlers/search_traces.go

Comment thread cmd/jaeger/internal/extension/jaegermcp/internal/handlers/get_span_details.go Outdated

graphite-app Bot reviewed Mar 18, 2026

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Comment thread cmd/jaeger/internal/extension/jaegermcp/internal/handlers/get_span_details.go

rite7sh added 2 commits March 18, 2026 13:11

jaegermcp: validate maxSpanDetailsPerRequest and fix tests

3ecb2b7

Signed-off-by: Ritesh Tripathi <ritesh6263tripathi@gmail.com>

Copilot AI review requested due to automatic review settings March 18, 2026 13:30

rite7sh force-pushed the fix/mcp-config-limits branch from a6babd7 to 3ecb2b7 Compare March 18, 2026 13:30

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jkowall requested a review from Copilot March 18, 2026 15:12

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Comment thread cmd/jaeger/internal/extension/jaegermcp/internal/handlers/get_span_details.go Outdated

Comment thread cmd/jaeger/internal/extension/jaegermcp/internal/handlers/search_traces.go

yurishkuro reviewed Mar 18, 2026

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Comment thread cmd/jaeger/internal/extension/jaegermcp/internal/handlers/get_span_details.go Outdated

jaegermcp: align validation with config and centralize span limit check

b00175a

Signed-off-by: Ritesh Tripathi <ritesh6263tripathi@gmail.com>

yurishkuro approved these changes Mar 18, 2026

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yurishkuro added changelog:experimental Change to an experimental part of the code and removed changelog:bugfix-or-minor-feature labels Mar 18, 2026

yurishkuro changed the title ~~jaegermcp: enforce config-driven limits in MCP handlers~~ [jaegermcp] Enforce config-driven limits in MCP handlers Mar 18, 2026

yurishkuro enabled auto-merge March 18, 2026 18:15

yurishkuro added this pull request to the merge queue Mar 18, 2026

Merged via the queue into jaegertracing:main with commit bb7318d Mar 18, 2026
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github-actions Bot added the waiting-for-author PR is waiting for author to respond to maintainer's comments label Mar 18, 2026

lopster568 mentioned this pull request Apr 10, 2026

[jaegermcp] Expose service names in search_traces trace summaries #8339

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[jaegermcp] Enforce config-driven limits in MCP handlers#8194

[jaegermcp] Enforce config-driven limits in MCP handlers#8194
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rite7sh commented Mar 18, 2026

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rite7sh commented Mar 18, 2026

Which problem is this PR solving?

Description of the changes

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