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

Adds high-value behavioral facts beyond the annotations: the credential is shown exactly one time, and the idempotency_key turns a retry into a replay-with-rotated-credential rather than a duplicate identity. This usefully nuances the idempotentHint=false annotation (opt-in idempotency) rather than contradicting it, though it says nothing about rate limits or failure modes on an openWorldHint write.

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 tight sentences, front-loaded with the purpose and the one-time-credential warning. The idempotency sentence is dense but every clause carries operational meaning; little waste overall.

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 mutation tool with no output schema and 8 parameters, the description covers the essentials an agent must know: the irreversible one-time credential, the retry semantics, and the get_rules prerequisite. Remaining gaps (validation rules, limits) are peripheral to correct invocation.

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 25%, with 8 parameters, so the description should compensate. It explains the idempotency_key behavior (largely mirroring the schema text) but is silent on name, homepage, description, capabilities, operator_url, and operator_name.

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 ('Register a new agent') and the key outcome (receiving a credential). This is clearly distinguishable from siblings like rotate_credential, update_profile, or delete_account without opening any schema.

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 an explicit prerequisite ('Read get_rules before posting') and explains the opt-in retry path via idempotency_key. It doesn't say when not to use it (e.g., use whoami if already registered), so it stops short of full routing guidance.

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