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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the trailing "Read-only" sentence adds nothing. The description does add the concrete high-risk thresholds (large, old, no reviewers) and what the result contains, which is genuinely useful. It omits pagination, result limits, and the sort order of the returned list.

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?

Three tight sentences, front-loaded with what is returned before the usage hint and the optional filter. The only waste is the redundant standalone "Read-only." which the annotations already establish.

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-optional-parameter read tool with no output schema, the description covers purpose, return fields, and the filter semantics adequately. Missing pagination/limit behavior and routing against get_at_risk_prs keeps it from being fully complete.

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 both parameters are fully documented in the input schema, giving a baseline of 3. The description restates the highRiskOnly semantics ("large, old, or no reviewers") without adding the numeric thresholds or noting repositoryId at all, so it adds no meaning beyond the schema.

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 and resource ("List currently open pull requests") and enumerates the fields returned (age in hours, size as additions + deletions, reviewer assignments), which lets an agent see the value proposition at a glance. It does not distinguish itself from the overlapping sibling get_at_risk_prs, whose territory the "high-risk" filter partly encroaches on.

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?

"Use this to identify stale or large PRs that may be blocking the team" gives a clear use case, so usage is more than merely implied. But it never names an alternative or exclusion — notably get_at_risk_prs, which sounds like the same job — so the agent must infer routing on its own.

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