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

Annotations already establish that this is a read-only, non-destructive operation, and the description adds useful context beyond that: a 64 KB cap on file reads and 'This call asks no human', which matters given the sibling approval tools. It doesn't say whether directory listings are truncated or paginated, which is the remaining gap.

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?

Two short sentences, front-loaded with the primary capability and its size constraint. Nothing is padded or repeated from the name.

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?

There is no output schema, so the description ideally should say what a directory listing returns (file paths only, or names plus metadata). That omission is minor against annotations that already convey the safety profile and a schema that documents every parameter.

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 all four parameters (ref, path, match, repository) are already documented in the schema, including the glob syntax and default branch behavior. The description reinforces the path semantics but adds no syntax or format detail beyond what the schema provides, 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?

States a specific verb and resource ('List a connected GitHub repository's files') and covers both modes of operation (list a directory, read a single file). No sibling tool overlaps with this capability, so the agent can select it unambiguously.

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 list-vs-read distinction through the path parameter ('List ... at a path, or read one file') and notes 'Omit for the top', which gives clear usage context. It stops short of explicit when-not guidance, but there is no competing sibling that would need routing away from.

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