fix(openapi): disambiguate colliding truncated tool names - #7284

Problem

Fixes #7281.

Gemini limits function names to less than 64 characters, so
OperationParser.get_function_name() and RestApiTool.__init__ both hard
truncate the generated tool name to 60 characters. Codegen-style OpenAPI
specs routinely produce long operationIds that share a long common
prefix, so distinct operations can truncate to the exact same name.

When that happens in OpenAPIToolset._parse, every colliding operation
produces a RestApiTool with the same .name. LlmRequest.append_tools
still sends a FunctionDeclaration for each tool, but tools_dict keeps
only the last one registered, so the model gets duplicate declarations with
one name while every call is routed to the last-registered operation's
endpoint — the earlier endpoint(s) become silently unreachable.

Fix

OpenAPIToolset._parse builds every RestApiTool for a given spec in one
place and therefore has full visibility into the whole toolset. After a
tool's name is generated, check it against the names already produced for
this toolset; on a collision, append a short numeric suffix (_2, _3,
...) and truncate so the final name still fits in 60 characters.

This is a minimal, additive change scoped to OpenAPIToolset._parse — it
does not change get_function_name() or RestApiTool.__init__, which have
no visibility into sibling operations and can't dedupe on their own.

Test plan

Added test_openapi_toolset_disambiguates_colliding_truncated_names in
tests/unittests/tools/openapi_tool/openapi_spec_parser/test_openapi_toolset.py,
using two operations whose operationIds share a 63-character prefix
(mirroring the issue's repro) and differ only after the 60-char truncation
point. It asserts the toolset produces two distinct tool names, each ≤60
chars, and that both original endpoints remain reachable via get_tool().

Confirmed the test fails without the fix (reverted just the source file
with git checkout HEAD~1 -- src/.../openapi_toolset.py and reran):

$ python -m pytest tests/unittests/tools/openapi_tool/openapi_spec_parser/test_openapi_toolset.py::test_openapi_toolset_disambiguates_colliding_truncated_names -q
F
AssertionError: Tool names collided: ['list_all_company_organization_department_users_by_filter_cri', 'list_all_company_organization_department_users_by_filter_cri']
assert 2 == 1
1 failed in 1.00s

With the fix restored:

$ python -m pytest tests/unittests/tools/openapi_tool/ -q
342 passed, 38 warnings in 3.96s

pre-commit (ruff, isort, pyink, addlicense, codespell, etc.) was run
against the changed files; the only failing hook
(check-new-py-prefix, demanding a unit guide for
src/google/adk/memory/_sqlite_memory_service.py) is pre-existing and
unrelated to this change — that file was added in an earlier commit
(9625b06c) not touched here.

AI assistance disclosure

This change was authored with the assistance of Claude Code (Anthropic).

🤖 Generated with Claude Code