What changed, and which symbols it touched

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden and discloses a prerequisite ('Requires a git checkout'), a cost/behavior trait ('without pulling the patch into context' indicating it is cheap and does not load the full patch), and the output structure. It does not explicitly state it's read-only but 'Summarize' implies no side effects; it lacks details on error conditions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is exactly two sentences: the first packs the core purpose and output, the second gives the use case and prerequisite. It is front-loaded, specific, and contains no filler or repetition.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's simplicity (two optional params, no output schema), the description is complete: it explains what it returns (counts and symbol locations), when to use it (start of session on dirty repo), and a prerequisite ('Requires a git checkout'). There are no critical gaps for agent selection or invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already documents both parameters fully (100% coverage), so the description need not compensate. It adds only a redundant clarification of `base` ('or a diff against base') but offers no new meaning for `limit` or parameter syntax, thus meeting the baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb 'Summarize' and clearly identifies the resource as the 'working-tree diff' with two explicit output components: '+added/-deleted counts' and 'enclosing functions/classes each hunk lands in.' This distinguishes it from sibling tools like 'snapshot' or 'outline_file' that focus on structure rather than diffs.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear context: 'The cheap way to start a session on a dirty repo,' and contrasts with 'without pulling the patch into context,' implying a lightweight alternative to reading the full diff. However, it does not name specific sibling alternatives or explicit exclusions, so it falls short of the highest bar.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.