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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds useful scope detail by listing what the response aggregates (mergeability, per-file diff stats, three flavors of comment threads), but says nothing about pagination of comments or response size for large PRs.

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 with the verb and resource first, followed by the returned fields. No filler, no repetition of the title.

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 usefully compensates by enumerating the returned data. It is a simple two-parameter read tool with full schema coverage, so the description is nearly complete; only the aggregation size/pagination of comments is left unaddressed.

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% and both parameters (repo, number) are fully documented in the schema, including the owner/name and URL formats, so the description carries no additional parameter burden. It adds no syntax or format detail beyond the schema, making the baseline of 3 appropriate.

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?

Specific verb ('Get') plus resource ('one GitHub pull request') with an enumeration of the sub-resources returned: description, mergeability, diff stats per file, reviews, comments, review comments. The singular 'one' implicitly separates it from github_list_prs, but no sibling is named explicitly, which keeps it short of a 5.

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: fetching a single PR by repo/number versus listing them. There is no explicit 'use this when' statement, no mention of github_list_prs as the alternative for browsing, and no guidance on when the comment/review payload is overkill.

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