PDF info

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so 'Changes nothing' largely restates structured data. What the description does add is the scope of inspection, notably that password protection is detected — a behavioral fact not present in annotations. The remaining gap is what happens when the file is encrypted or unreadable.

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?

One sentence, front-loaded with the verb and resource, followed by the precise list of returned facts and the read-only guarantee. 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?

An output schema exists, so return values need no elaboration, and the annotations fully cover the safety profile. The one unresolved point specific to this tool — whether a password-protected file is still inspected or raises an error — is left ambiguous.

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 at 100% schema description coverage, and the schema already spells out that the path must be absolute or start with ~/. The description adds nothing about the path argument, so the baseline 3 for schema-covered parameters 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?

States a specific verb (reads) and resource (a PDF) and enumerates exactly what is reported: page count, file size, first page size in points, password-protection status. That enumeration clearly separates it from every sibling, all of which mutate PDF structure (merge, split, rotate, delete, reorder, duplicate).

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?

Usage is only implied: 'Changes nothing' signals this is the non-mutating inspection option among mutating siblings, but the description never says when to call it (e.g., before splitting or extracting) or names any alternative. An agent can infer the role but must do the reasoning itself.

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