updatePullRequest

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

Annotations already indicate destructiveHint=true, so the description doesn't need to restate that. It adds the behavioral detail that assignees and labels are applied through the issue endpoint, which is useful context. However, it does not disclose other behavioral traits like whether the operation is atomic, what happens to existing values for unspecified fields, or any permission requirements.

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 a single sentence that front-loads the main purpose and key fields, then adds a critical implementation note. There is no redundancy or fluff; every part 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?

For a mutation tool with no output schema, the description covers the primary fields and the special handling of assignees/labels. However, it does not mention the return value or any side effects (e.g., what happens if the base branch change causes conflicts). Given the tool's complexity (9 params) and lack of output schema, a bit more detail on expected outcomes would improve completeness.

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 coverage is 100%, so every parameter already has a description. The description adds meaningful context by explaining that assignees and labels are routed through the issue endpoint, which clarifies how those parameters are handled beyond the schema's simple field descriptions. This exceeds the baseline of 3.

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 clearly states the tool updates a pull request and enumerates the mutable fields (title, body, state, base branch). It also adds the nuance that assignees and labels are handled through the issue endpoint, which is a specific detail that differentiates this tool from generic update operations and clarifies its scope.

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 provides no explicit guidance on when to use this tool versus alternatives like getPullRequest or createPullRequest. It does not mention any exclusions or scenarios where this tool should not be used. The only usage note is about the issue endpoint for assignees/labels, which is more of an implementation detail than a usage guideline.

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