Inspect a PDF

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

The description asserts 'Read-only, never modifies the file', while the annotations declare readOnlyHint=false, which explicitly marks the tool as not a read-only operation. This is a direct conflict between the prose and the structured safety metadata, so per the rubric the score is 1 and the contradiction is flagged.

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?

A single front-loaded sentence with an enumerated return list; nothing is padded. The leading 'Call this tool to' is mild filler, but the payload arrives immediately and every clause carries information.

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 correctly carries the return-value burden and enumerates the fields an agent will receive, which is the key requirement here. It does not state behavior for malformed or password-protected files, leaving a small gap for a single-parameter inspection tool.

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?

There is a single parameter and schema description coverage is 100%, so the schema already documents the 'path' argument including tilde expansion and relative-path resolution. The description adds nothing further about the parameter, which is the expected baseline when the schema carries the burden.

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 names a specific verb+resource (inspect a PDF) and enumerates exactly what the inspection yields: page count, page sizes in points/mm, paper name, metadata fields, and encryption state. That enumeration implicitly separates it from pdf_count, pdf_pages, and pdf_text, but no sibling is named explicitly, so it stops short of full sibling differentiation.

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 opening imperative 'Call this tool to inspect a PDF' implies the usage context but offers no when-not guidance and no routing against near-siblings such as pdf_count, pdf_pages or pdf_text. The 'Free tier: unlimited' note is useful operational context but is not selection guidance.

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