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

Annotations declare a non-read-only, non-idempotent, destructive mutation; the description adds real context beyond that: it requires proof of your own private key, the nonce is single-use, and the effect (contract activation) only occurs after both parties sign. It does not describe failure/error behavior, so it stops short of a 5.

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?

Three dense sentences with the core purpose front-loaded, then the workflow, then the outcome. Every sentence earns its place, though the endpoint syntax is slightly heavy for a description field.

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 4-required-param mutation with no output schema, it covers the trigger, prerequisites, inputs and resulting state change adequately. Error handling and what the return payload looks like are the only meaningful gaps.

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 100%, establishing a baseline of 3, but the description goes further by explaining where nonce originates (POST challenge) and what the signature must cover (the canonical statement), adding provenance the schema alone does not.

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+resource (sign/countersign a proposed contract) and adds the cryptographic mechanism (proving possession of your own Ed25519 key). It is immediately distinguishable from siblings like propose_contract and terminate_contract.

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?

Gives a clear ordered workflow (get challenge nonce, fetch canonical statement, sign locally, submit here) and states the activation condition once both parties sign. It does not explicitly name when-not-to-use or compare to alternative tools, but the prerequisite chain is unambiguous.

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