Read pull request diff

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

Annotations already declare readOnlyHint=true, but the description adds significant transparency beyond that by stating it never checks out code, runs tests, requests approval, or modifies GitHub. It also discloses that the result reports truncation and byte counts, and includes a SHA-256 fingerprint, which is useful behavioral detail not captured in the schema.

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 two sentences with no redundancy. The first sentence front-loads the core function and output characteristics; the second immediately clarifies the read-only nature and non-modification stance. Every word earns its place.

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 moderate complexity (5 parameters, mostly simple), the description explains what the tool returns (bounded diff, truncation info, byte counts, fingerprint), its read-only nature, and its safety guarantees. An output schema exists, so return details are covered. The description is sufficient for an agent to select and invoke the tool 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?

Input schema covers all parameters with descriptions (100% coverage), so the baseline is 3. The description adds minimal parameter-specific nuance (e.g., 'bounded' hints at max_bytes behavior), but it does not elaborate on formats or defaults beyond what the schema already states, so it neither compensates nor degrades.

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?

Description clearly states the tool returns a bounded unified diff or patch for the exact base and head commit SHAs of a PR, distinguishing it from siblings that list PR metadata, files, or commits. It also specifies that it is read-only and never modifies state, making its purpose unambiguous.

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?

Provides clear context by describing exactly what it returns and explicitly listing actions it never performs (checkout, tests, approval, modifications), which helps agents avoid misuse. However, it does not explicitly name alternative tools for cases where a read-only diff is not suitable, so it lacks explicit when-not-to-use guidance.

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