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

Annotations are all false, providing minimal safety signals. The description adds valuable non-obvious context: the cryptographic nature (PAdES), the API key requirement, and the conditional return of setup instructions. However, it does not disclose other behaviors like idempotency, side effects on the render, or failure modes beyond the missing key.

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?

Two sentences, front-loaded with the primary action and the key condition. No filler words; every phrase adds information. The conditional 'Without a key' is an efficient way to describe the no-key scenario.

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 has 7 parameters and no output schema. The description covers the prerequisite and fallback output, but does not mention what a successful signing returns (e.g., a signed PDF, a status object, or a render ID). It also omits any warnings about irreversibility or the need for the render to be in a valid state. Given the parameter richness is handled by the schema, this gap prevents a higher score.

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%, and each parameter has a clear description in the schema itself. The tool description adds no parameter-specific meaning beyond what the schema documents, but that is acceptable because the schema carries the full burden. A baseline of 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 ('sign') and resource ('existing render') with the method ('PAdES'), clearly distinguishing it from sibling tools like render_pdf (creates renders) and verify_pdf_signature (verifies). The phrase 'existing render' reinforces it is a follow-on action.

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 states the prerequisite ('when a Kamy API key is configured') and the fallback behavior when the key is missing. It implies usage on existing renders rather than new ones, which distinguishes it from render_pdf, but it does not explicitly name alternative tools or when not to use it (e.g., for verification).

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