File metadata

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

Annotations already establish read-only and idempotent behavior. The description adds useful behavioral detail beyond those annotations: it guarantees path/name/size/type, makes output type-dependent, and specifies flattening. It does not cover error or unsupported-type behavior, but the annotations lower the burden.

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?

The description is two sentences with no filler: it front-loads the purpose, lists supported formats, then states the guaranteed output and the flattening behavior. Every phrase earns its place.

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?

Given an output schema exists and the annotations cover safety, the description supplies sufficient context: supported types, guaranteed core fields, and output flattening. Minor ambiguity around unsupported file types and path expectations 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?

The input schema has only a required string 'path' with no description, and the tool description does not define path syntax, scope, or allowed forms. The description's mention of 'path' in the output is an indirect clue, and the single conventional parameter is understandable, but with 0% schema description coverage the description does not fully compensate.

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?

The description clearly identifies the tool as a file metadata provider and enumerates supported formats (epub, m4b, PDF, DOCX) and common output fields. It does not use an explicit verb like 'retrieves' or 'returns', and it does not explicitly contrast itself with sibling tools, so it stops 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?

The format list gives concrete applicability: agents can infer they should use this tool when needing metadata for epub, m4b, PDF, or DOCX files. It does not explicitly name alternatives or say when not to use it, so it lacks the explicit when/when-not guidance required for a 5.

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