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

Annotations already declare destructiveHint=true and idempotentHint=false, so the safety profile is covered. The description earns some credit for 'applies immediately,' which tells the agent there is no staging or confirmation step, but it omits what closing implies (whether the branch is preserved, whether it can be reopened, or what collaborators see).

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?

A single front-loaded sentence that states the action, its mechanism, and its timing with no waste.

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 two-parameter mutation tool with full annotations and an output schema, the description gives enough to select and call it correctly. The only shortfall is the absence of any note on post-rejection state or permissions.

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%, including the nuanced defaulting behavior of the ledger parameter and the meaning of prNumber, so the schema carries the parameter semantics. The description adds nothing about either parameter and does not need to.

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 (reject) and resource (pull request) and clarifies the mechanism: closing without merging. The phrase 'without merging' implicitly separates it from the sibling mergePullRequest, though it never names that sibling directly.

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?

Usage is only implied by the contrast with merging; there is no explicit statement of when to reject versus when to merge or close by other means, and no mention of preconditions such as required permissions or PR state.

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