feat(mcp): record safe tool input names

[gesh]

💡 Motivation and Context

MCP server owners need to measure which input names agents use. This must not expose argument values or unknown field names.

This PR ports the input-name and alias contract from @posthog/mcp 0.19.0 and 0.20.0. It adds $mcp_input_keys, $mcp_input_aliases_used, and a helper for custom dispatchers.

💚 How did you test it?

• uv run pytest -q posthog/test/mcp --timeout=30
• uv run ruff check posthog/mcp posthog/test/mcp/test_tool_input.py posthog/test/mcp/test_features_m4.py
• uv run mypy --no-site-packages --config-file mypy.ini posthog/mcp | uv run mypy-baseline filter
• make public_api_check

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran sampo add to generate a changeset file

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Codex implemented the agreed Python port. The implementation keeps schemas isolated by session and redacts unknown names by default.

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Created with PostHog Desktop

[github-actions]

posthog-python Compliance Report

Date: 2026-09-29T13:11:50.856683+00:00
Duration: 259795ms

✅ All Tests Passed!

121/121 tests passed

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Capture_V1 Tests

✅ 95/95 tests passed

View Details

Test	Status	Duration
Endpoint And Method.Targets V1 Endpoint	✅	515ms
Endpoint And Method.Does Not Use Legacy Endpoints	✅	514ms
Required Headers.Has Authorization Bearer Header	✅	511ms
Required Headers.Has Content Type Json	✅	512ms
Required Headers.Has Posthog Sdk Info Format	✅	511ms
Required Headers.Has Posthog Attempt Header	✅	511ms
Required Headers.Has Posthog Request Id	✅	510ms
Required Headers.Has Posthog Request Timestamp	✅	512ms
Required Headers.Has User Agent	✅	511ms
Body Format.Body Has Created At And Batch	✅	511ms
Body Format.No Api Key In Body	✅	511ms
Body Format.No Sent At In Body	✅	511ms
Event Format.Event Has Required Root Fields	✅	511ms
Event Format.Event Uuid Is Valid	✅	512ms
Event Format.Event Timestamp Is Rfc3339	✅	511ms
Event Format.Non Utc Event Timestamp Is Converted To Utc	✅	514ms
Event Format.Distinct Id Is String	✅	511ms
Event Format.Distinct Id At Root Not Properties	✅	511ms
Event Format.Custom Properties Preserved	✅	512ms
Event Format.Set Properties Preserved	✅	511ms
Event Format.Set Once Properties Preserved	✅	511ms
Event Format.Groups Properties Preserved	✅	512ms
Event Format.Sdk Generates Uuid If Not Provided	✅	512ms
Event Format.Event Has Required Root Fields Batch	✅	518ms
Event Format.Event Uuid Is Valid Batch	✅	515ms
Event Format.Event Timestamp Is Rfc3339 Batch	✅	515ms
Event Format.Distinct Id Is String Batch	✅	516ms
Event Format.Distinct Id At Root Not Properties Batch	✅	515ms
Event Format.Custom Properties Preserved Batch	✅	516ms
Event Format.Set Properties Preserved Batch	✅	514ms
Event Format.Set Once Properties Preserved Batch	✅	516ms
Event Format.Groups Properties Preserved Batch	✅	515ms
Event Format.Sdk Generates Uuid If Not Provided Batch	✅	515ms
Batch Behavior.Multiple Events In Single Batch	✅	517ms
Batch Behavior.Batch Envelope Smoke	✅	517ms
Batch Behavior.Flush With No Events Sends Nothing	✅	508ms
Batch Behavior.Flush At Triggers Batch	✅	1013ms
Batch Behavior.Created At Reflects Batch Creation Time	✅	512ms
Deduplication.Generates Unique Uuids	✅	518ms
Deduplication.Different Events Same Content Different Uuids	✅	514ms
Deduplication.Preserves Uuid On Retry	✅	6521ms
Deduplication.Preserves Timestamp On Retry	✅	6521ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	6525ms
Deduplication.No Duplicate Events In Batch	✅	520ms
Header Behavior On Retry.Attempt Header Starts At One	✅	512ms
Header Behavior On Retry.Attempt Header Increments On Retry	✅	13528ms
Header Behavior On Retry.Request Id Preserved On Retry	✅	6521ms
Header Behavior On Retry.Different Requests Have Different Request Ids	✅	3022ms
Header Behavior On Retry.Request Timestamp Changes On Retry	✅	6522ms
Response Format Validation.Success Response Has Uuid Keyed Results	✅	513ms
Response Format Validation.Success Response Has Ok For Each Event	✅	516ms
Response Format Validation.Success No Retry After When All Ok	✅	514ms
Response Format Validation.Success Retry After Present When Retry Events	✅	1518ms
Response Format Validation.Success No Retry After When Drop Only	✅	515ms
Response Format Validation.Response Echoes Request Id	✅	511ms
Retry Behavior.Retries On 408	✅	6521ms
Retry Behavior.Retries On 500	✅	6521ms
Retry Behavior.Retries On 503	✅	8525ms
Retry Behavior.Retries On 504	✅	6522ms
Retry Behavior.Retryable Errors Have Retry After	✅	3517ms
Retry Behavior.Respects Retry After On Retryable Error	✅	11526ms
Retry Behavior.Does Not Retry On 400	✅	2515ms
Retry Behavior.Does Not Retry On 401	✅	2516ms
Retry Behavior.Does Not Retry On 402	✅	2516ms
Retry Behavior.Does Not Retry On 413	✅	2513ms
Retry Behavior.Does Not Retry On 415	✅	2517ms
Retry Behavior.Non Retryable Errors Have No Retry After	✅	2515ms
Retry Behavior.Implements Backoff	✅	22537ms
Retry Behavior.Max Retries Respected	✅	22539ms
Partial Batch Handling.Handles 200 Full Success	✅	2514ms
Partial Batch Handling.Handles 200 With All Ok	✅	3518ms
Partial Batch Handling.Does Not Retry Dropped Events	✅	3515ms
Partial Batch Handling.Does Not Retry Limited Events	✅	3516ms
Partial Batch Handling.Prunes Ok Events On Partial Retry	✅	6523ms
Partial Batch Handling.Prunes Dropped Events On Partial Retry	✅	6521ms
Partial Batch Handling.Retries Only Retry Events From Partial	✅	6522ms
Partial Batch Handling.Partial Retry Preserves Uuids	✅	6524ms
Partial Batch Handling.Partial Retry Attempt Header Increments	✅	6523ms
Partial Batch Handling.Partial Retry Request Id Preserved	✅	6524ms
Partial Batch Handling.Respects Retry After On Partial	✅	8521ms
Partial Batch Handling.Unknown Result Treated As Terminal	✅	3517ms
Partial Batch Handling.Mixed Ok Drop Limited No Retry	✅	3519ms
Compression.Sends Gzip Content Encoding	✅	512ms
Compression.No Content Encoding When Disabled	✅	510ms
Compression.Compressed Body Is Decompressible	✅	511ms
Error Handling.Does Not Retry On Unknown 4Xx	✅	2514ms
Event Options.Cookieless Mode Override	✅	513ms
Event Options.Disable Skew Correction Override	✅	511ms
Event Options.Process Person Profile Override	✅	513ms
Event Options.Product Tour Id Override	✅	511ms
Event Options.Unset Options Omitted	✅	511ms
Event Options.Options Override In Batch	✅	516ms
Geoip And Historical Migration.Geoip Disable Injected Into Properties	✅	515ms
Geoip And Historical Migration.Historical Migration Set In Body	✅	511ms
Geoip And Historical Migration.Historical Migration Absent By Default	✅	511ms

Capture_Ai Tests

✅ 5/5 tests passed

View Details

Test	Status	Duration
Routing.Capture Ai Posts To Ai Endpoint	✅	511ms
Routing.Capture Does Not Reroute Ai Named Events	✅	511ms
Identity.Capture Ai Event Has Uuid	✅	511ms
Identity.Capture Ai Keeps Supplied Uuid	✅	512ms
Timestamp Format.Non Utc Event Timestamp Is Converted To Utc	✅	512ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	13ms
Request Payload.Flags Request Uses V2 Query Param	✅	8ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	9ms
Request Payload.Flags Request Omits Authorization Header	✅	8ms
Request Payload.Token In Flags Body Matches Init	✅	8ms
Request Payload.Groups Round Trip	✅	8ms
Request Payload.Groups Default To Empty Object	✅	7ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	8ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	8ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	8ms
Request Lifecycle.No Flags Request On Init Alone	✅	3ms
Request Lifecycle.No Flags Request On Normal Capture	✅	508ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	15ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	9ms
Retry Behavior.Retries Flags On 502	✅	313ms
Retry Behavior.Retries Flags On 504	✅	315ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	512ms

Feature_Flags_Local_Evaluation Tests

✅ 4/4 tests passed

View Details

Test	Status	Duration
Versioned Boolean Matching.Matching Version Missing	✅	60ms
Versioned Boolean Matching.Matching Version 1	✅	56ms
Versioned Boolean Matching.Matching Version 2	✅	56ms
Versioned Boolean Matching.Version Only Reload 1 2 1 2 Missing	✅	30ms

[greptile-apps]

[Medium risk] Adds safe tool input field-name recording to analytics events.

The PR is not safe to merge until schema lookup is isolated across clients and remains valid after conversation anchoring, and alias reporting respects the recording filter.

_{Reviews (1) · Last reviewed commit: "feat(mcp): record safe tool input names"}