repo_impact

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context beyond annotations: grounded citations, the use of a code graph, deterministic execution, and zero side effects, along with the structured output nature.

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 well-structured and front-loaded, starting with the core purpose before moving to usage, exclusions, and output. Every sentence contributes value, and the 'When to use'/'When NOT to use' formatting makes it easy for an agent to parse.

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?

For a read-only analysis tool with no required parameters and full schema coverage, the description covers purpose, inputs, use cases, exclusions, and output format. Even without an output schema, it tells the agent what kind of report to expect and what content the report includes.

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 the schema already documents all five parameters and the format enum. The description adds contextual behavior ('diff impact', 'PR summary') but does not need to elaborate on each parameter; this is appropriately at 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 and resource: 'Analyze PR or git diff impact against a base branch using the code graph.' It lists concrete detection targets (changed symbols, affected APIs, callers, test coverage, blast radius) and explicitly distinguishes itself from generic lexical search via repo_search.

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?

It provides explicit 'When to use' guidance with concrete scenarios: assessing PR risk, planning test execution, evaluating breaking API changes, and investigating diff blast radius. It also gives a clear 'When NOT to use' exclusion and names the alternative tool, repo_search.

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