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

The description reveals server-side verification of proof of possession, a public publication URL (/.well-known/tango-worker-keys/{worker_id}.json), and rejection of private-key submissions. These behaviors go well beyond the annotations (readOnlyHint=false, destructiveHint=false) without contradicting them.

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?

Four dense sentences, each carrying distinct information: flow position, required payload, verification/publication behavior, and mode-selection guidance. It is front-loaded with the most important constraint ('Submit ONLY your ... PUBLIC JWK').

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?

It covers the main protocol flow, security constraints, and the choice between attested and delegated mode, which matters for correct invocation. It omits a description of return responses or error cases, but there is no output schema and the parameter schema fills most remaining 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?

The description reinforces that public_key_jwk must be public-only (no private key) and ties signed_nonce to the request_key_challenge nonce, which is useful beyond the schema's 'base64url Ed25519 signature' text. Worker_id is only implied through the URL, but schema coverage is already 75%, so the description need not restate every field.

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 identifies a concrete action ('register'), a resource ('my public signing key'), and its role in a larger flow ('Step 2 of attested mode'). It distinguishes itself from sibling key tools by specifying the public JWK submission and proof-of-possession verification, so an agent won't confuse it with issue/rotate/revoke.

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?

It explicitly frames when the tool applies ('Step 2 of attested mode') and gives a when-not condition: 'Only register an attested key if you can persist the private key across sessions; otherwise use delegated mode'. It also warns against private-key submissions, providing a clear safety boundary.

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