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

The description states 'Read-only, never modifies the file,' but the annotation readOnlyHint is false. This is a direct contradiction. Since the description contradicts the annotation, it scores a 1 and is flagged as an annotation contradiction.

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 concise and front-loaded: it states the purpose, lists the inspected attributes, and adds the read-only note and free tier in two sentences with no fluff. Every sentence 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?

The tool is simple (one parameter, no output schema), and the description covers the return information. However, it omits the prerequisite that the file must be uploaded via pdf_upload (which is only in the schema), and does not mention error conditions or how the results are structured. Given the simplicity, it is adequate but has gaps.

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 fully documents the path parameter (100% coverage), so the description does not need to add parameter details. The description adds nothing about path format or constraints beyond the schema, matching the baseline of 3.

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 states the tool inspects a PDF and enumerates what it returns (page count, sizes, paper name, metadata, encryption). It has a specific verb and resource, but does not explicitly distinguish it from sibling tools like pdf_count or pdf_pages, so it misses the top score.

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 on when to call it ('Call this tool to inspect a PDF') and notes it is read-only. However, it does not mention alternatives or conditions for using a different tool, so it stops short of full guidance.

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