Sign PDF (RSA / ECDSA, PAdES)

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

Annotations are minimal (all false), so the description carries the burden. It discloses the auto-injection behavior, algorithm support, and conditional key requirements. However, it does not mention potential side effects (e.g., whether the PDF is modified in-place or what happens if the PDF is already signed). The description is mostly transparent but misses some behavioral details.

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 succinct with no redundant information. It front-loads the primary action, then provides updates, requirements, conversion tips, and a follow-up suggestion. Every sentence adds value.

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?

Given the complexity (14 parameters, 3 required, output schema present), the description covers the essential flow and key requirements. It lacks guidance on optional metadata parameters, but those are less critical. An output schema exists, so return values need not be detailed. Overall, it is fairly complete for most use cases.

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 description adds significant meaning for the core parameters (pdfBase64, algorithm, certDerBase64, and the conditional key parameters) and explains the autoInjectPlaceholder default. However, it does not describe optional parameters like signerName, reason, location, contactInfo, signingTime, outputMode, or outputPath, which are only partially covered in the schema (57% coverage). The description could compensate more for the missing schema descriptions.

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 applies a PAdES-compatible CMS digital signature to a PDF. It distinguishes from sibling tool prepare_signature_placeholder by explaining that auto-injection renders that step optional. The specific resource (PDF) and action (sign) are evident.

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 explicitly says when to use this tool (to sign any PDF in one call) and when not to (if you want to customize placeholder appearance, use prepare_signature_placeholder). It also recommends calling verify_pdf after signing. Conversion commands for keys are provided, guiding the agent on required input preparation.

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