skeleton

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

Annotations already declare readOnly/idempotent/non-destructive, so the description's job is to add behavior it can't infer — and it does: signatures are normalized summaries, line ranges are included, and the output is explicitly not safe as an exact edit anchor. It doesn't cover failure modes (unsupported file types, missing paths) or output size limits, so not a 5.

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?

Three tight sentences: what it returns, what it returns alongside (line ranges), and the critical caveat plus alternative. The most decision-relevant constraint (not an edit anchor) is front-and-center rather than buried.

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?

With no output schema, the description carries the burden of explaining the return value, and it does reasonably well (signatures, methods, type definitions, line ranges). Minor gaps remain around output shape details and behavior on unsupported languages or empty files, but an agent has enough to call it correctly.

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?

Schema description coverage is 100%, so all three parameters (root, file_path, exported_only) are already documented, including the worktree caveat for root. The description adds no parameter-level meaning, so the baseline 3 applies.

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?

States a specific verb and resource ('Get detailed function signatures, class methods, and type definitions of a specific file') and adds a clear scope qualifier ('WITHOUT reading the full body'). An agent can distinguish this from body-reading siblings like search/grep/exact_references purely from the description.

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?

Explicitly routes the agent: this tool is for API surface, and 'use context(targets:[{file,start,end}]) for source text before editing' names the alternative and the condition that selects it. It also warns against using the output as an edit anchor, which is a concrete when-not rule.

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