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

Annotations are absent, so the description must carry the behavioral burden. The verb 'Read' implies no modification, but the description does not explicitly state that the file is unchanged, what the return structure looks like, or potential errors (e.g., invalid PDF). This is adequate for a simple getter but not fully transparent.

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, well-structured sentence that leads with the verb and resource, then concisely lists the relevant metadata fields. No filler or redundancy.

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 and the schema covers the only parameter, but with no output schema and no annotations, the description should ideally state what the returned metadata looks like (e.g., a structured object) and confirm the operation is non-destructive. It is complete enough for basic use but leaves some ambiguity.

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 the single 'file' parameter and its base64/max-size details. The description adds no extra meaning about the parameter itself, just about the output, so the baseline 3 applies.

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 uses a specific verb ('Read'), a clear resource ('a PDF's document properties'), and enumerates the exact fields (title, author, subject, keywords, etc.). It is unmistakably distinct from sibling tools like set_pdf_metadata and the page-manipulation tools.

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 context is clear: use this when you need to inspect a PDF's metadata. It does not explicitly name alternatives or state when not to use it, but the read-only intent and the sibling set_pdf_metadata make the intended usage obvious enough.

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