Annotate all 30 lens tools with ToolAnnotations

[tarungarg546]

Problem

All 30 tools in lens_mcp/server.py were declared as a bare @mcp.tool(). The word annotations did not appear anywhere in the package, so the advertised tool schemas carried no behavioural hints. A client has to assume an unannotated tool can write, so every lens tool looked write-capable and every lens call stopped to ask permission.

Change

Two module-level ToolAnnotations constants next to the FastMCP instance, applied at each decorator:

	readOnlyHint	destructiveHint	idempotentHint	openWorldHint	tools
READ_ONLY	True	False	True	True	27
WRITES_LOCAL_FILES	False	False	True	True	3

The three download_* tools (download_entity_logs, download_trace_logs, download_prompts) genuinely write .log/.txt files into the scratchpad dir, so they cannot claim readOnlyHint. They are non-destructive and idempotent — a repeat call overwrites the same per-SID paths. openWorldHint is True throughout because every tool hits the remote Lens API.

No tool bodies, signatures, or docstrings changed — the diff is the import, the two constants, and 30 decorator lines.

Verification

mcp.list_tools() returns 30 tools, all with annotations, and exactly the three download_* are non-read-only.

New tests/test_annotations.py (3 tests, same self-running style as test_stats.py) guards this:

• every tool has annotations
• the non-read-only set is exactly the three download_*
• nothing claims destructive; everything is idempotent and open-world

$ uv run python tests/test_annotations.py
ok   test_every_tool_is_annotated
ok   test_nothing_is_destructive_and_everything_is_open_world
ok   test_only_the_download_tools_are_not_read_only

0 failure(s)

tests/test_stats.py still passes (0 failures).

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