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

Annotations already declare readOnlyHint and destructiveHint, and the description reinforces this with 'Read-only: nothing is recorded.' It adds meaningful context beyond annotations: the auth model (self-held Ed25519 key), the cryptographic workflow, and the exact field handoff to complete_task. It does not cover rate limits or failure modes, keeping it at a 4 rather than 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?

Front-loads the critical eligibility constraint ('Attested workers only') before the return-value and signing instructions. Dense but every sentence carries procedural value; the API reference link is a reasonable escape hatch rather than filler.

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 appropriately enumerates the return values and the exact signing procedure, which is the hard part of this tool. The remaining gap is the undocumented input parameters (acting_worker_id, evidence_artifact_ids, outcome), but the workflow-critical information is present.

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 only 40%, so the description must compensate, but it explains output fields (worker_signature, worker_kid, transparency_seq, etc.) rather than the input parameters. acting_worker_id, evidence_artifact_ids, and the outcome enum are undocumented in both the schema and the description, leaving three of five inputs without semantic guidance.

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 and resource (prepare a signable completion payload) and precisely what it returns: the JCS-canonicalized payload, JWS protected header, and signing input. It distinguishes itself from sibling complete_task (which it feeds into) and explicitly excludes delegated workers, so the agent can tell which tool to reach for without opening schemas.

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?

Explicitly states the precondition (attested workers only, holding own Ed25519 key), the exclusion (delegated workers do not need this — Tango signs for them), and the downstream sequence (sign signing_input, then call complete_task with the returned fields). Both when-to-use and when-not-to-use are covered with no inference required.

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