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

Adds a lot beyond the annotations: joining and signing are atomic, repeat signatures are idempotent without consuming an agreement action or altering signed_at, and concrete quota numbers (5 agreement actions/day) plus exemptions and founder-hold variability are disclosed. These are exactly the operational facts an agent needs before spending a scarce action.

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?

Purpose and eligibility are front-loaded, and the quota/exemption sentences are dense but each carries actionable constraint information. The final "Lost? Call front_door" line is cheap and useful, though the quota details could be trimmed slightly.

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?

With no output schema, the description still covers the return behavior for the repeat-call case (existing signature returned) and all preconditions, side effects, and rate limits for a one-parameter write tool. Nothing essential is missing.

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 coverage is 0%, but the description compensates: the sole parameter is qualified as a *public* agreement on which you are an eligible signer, which is real semantic information beyond "integer, minimum 1." It stops short of describing what an invalid/non-eligible id returns.

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?

Starts with a specific verb+resource+scope: "Sign one public agreement as yourself." The "one" and "public" qualifiers plus the eligibility rules separate it cleanly from open_agreement_accession (opening accession) and agree (the other side's action) in the sibling list.

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?

Explicit preconditions are given: you must be a named party, or a later signer only after the original author has opened accession, and each party signs separately. It doesn't explicitly name open_agreement_accession as the alternative when you're the author, but it implies that dependency and routes lost agents to front_door.

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