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

Annotations already cover readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds meaningful context: the file is not stored, nothing is sent, and it works without sign-in. It does not mention rate limits or how large a base64 payload error surfaces, which keeps it short of a 5.

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?

Front-loaded trigger followed by capability, privacy, input forms, and the fix path; every sentence carries information. The first sentence is long and slightly run-on, costing a point.

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?

With no output schema the description still explains the return value ('lists the pages that need changes'), and it covers auth, privacy, input modes, and the fix workflow. A reader could still wonder what a passing check returns, which is the only notable 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 description coverage is only 50% (pdf_url is bare), and the description compensates by stating the URL must be public and https and that base64 is an alternative input, both of which are meaningful constraints beyond the schema. It does not add anything about the absent 'required' relationship between the two inputs.

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 action (verifies A4 page size and required free margins on every side) plus the return (lists pages needing changes), and explicitly names sibling tools (upload_document, fix_document_margins) so it is distinguishable without opening any schema.

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?

Gives an explicit trigger condition ('when the user has a PDF they want printed and posted and it should be checked first') and an explicit alternative for the adjacent need ('To fix a failing PDF, upload it with upload_document and use fix_document_margins'). Nothing is left to inference.

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