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

With no annotations, the description supplies substantial behavioral context: cryptographic validity versus trust-chain assertions, post-signing edit detection, the unsigned-PDF edge case, signature format, upload limitations, billing, and API-key charging. These details go well beyond merely implying that verification reads and signing mutates.

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 operation distinctions and important trust limitation are front-loaded, and nearly all of the text conveys actionable information. However, combining pricing, authentication, and a seven-parameter glossary into one dense paragraph reduces scanability.

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?

For a complex dual-mode tool with no annotations and an undescribed schema, this covers nearly all selection and invocation needs, while the output schema can carry return structure. It still leaves the nullable op's default behavior unstated and does not clarify whether signing produces a new file or modifies the source.

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?

Despite 0% schema description coverage, the description explains all seven parameters, including op values, PKCS#12 encoding and formats, conditional requirements, empty-password handling, and optional sign-only metadata. The one-binary-upload constraint adds further invocation meaning absent from the schema.

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 specifies two concrete operations on PDF signatures: verifying every signature and adding a PAdES-B signature from a PKCS#12 bundle. It also details what verification checks, but it does not explicitly distinguish this tool from the broader pdf_tools sibling.

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 op=verify and op=sign sections provide clear operation-specific context, while the conditional p12_base64 requirement and multipart restriction guide signing calls. There is no explicit when-not-to-use guidance or alternative tool for other PDF operations or trust-chain validation.

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