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

Annotations already declare readOnlyHint, so safety is covered. The description adds real behavioral context beyond that: the empty-list caveat, the absence of direction in a relationship, and the note that these are relationships the deploy graph cannot infer. Return format is still unspecified.

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?

Purpose is front-loaded, then the scoping and caveats follow. It is on the longer side (five sentences) but each carries substantive information; no filler sentences.

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 one-parameter read tool with no output schema, the description is nearly complete: it explains what the list contains, when it's consulted, and the misleading-empty-result edge case. Only the return shape is left unspecified, which is a minor gap.

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 the schema description already documents installation_id, including that list_credentials reports it for GitHub App credentials. The description only implies the GitHub App installation scope and adds no syntax or format detail beyond the schema, so baseline 3 applies.

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?

Names a specific verb+resource (list related repositories) and pins the scope precisely: relationships an org admin declared for AI code review, under one GitHub App installation. It also clarifies the concept against the sibling pair relate_repositories/unrelate_repositories by defining what a 'relationship' is.

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?

Explains the context in which the list matters (a PR that removes something triggers a search of related repos) and gives the crucial exclusion that an empty list does NOT imply nothing is related, since two other sources supply relations. It stops short of naming the sibling tools to mutate relations or the other sources explicitly.

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