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

Annotations are all false, so the description carries the burden. It discloses that rotation is additive, that a new file is written, and that the free tier is limited to 30 pages. It doesn't mention whether the original file is left untouched, but 'writes a new file' implies it. The download link validity is in the schema, not the description, but the description adds useful behavioral context.

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 sentences, each earning its place: the action and direction, the additive behavior and use case, and the output and free-tier limit. Front-loaded with the core action.

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 5-param tool with no output schema, the description covers the core behavior, the use case, and the free-tier limit. It doesn't explain the return value (download link) but the schema's out_path description covers that. It also doesn't mention overwrite behavior, but the schema covers it. Overall, complete enough for an agent to call correctly.

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 the schema already documents all parameters. The description adds the meaning of positive degrees (clockwise) and that rotation is added to existing rotation, which complements the schema. However, it doesn't add much beyond the schema's parameter descriptions, so baseline 3 is 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?

The description states a specific verb ('turn pages'), the resource (PDF), and the key constraint (multiple of 90 degrees, clockwise for positive). It also distinguishes itself from sibling tools by mentioning rotation and writing a new file, which is not covered by pdf_merge, pdf_split, pdf_reorder, etc.

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 description gives clear context: use for sideways scans, rotation is added to existing rotation, and it writes a new file. It doesn't explicitly name alternatives or when not to use it, but the context is strong enough for an agent to select it appropriately among siblings.

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