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

No annotations are provided, so the description carries the behavioral disclosure burden. It discloses that the call merges without touching other fields, that the value is never echoed back, and that proof requirements are enforced wit patron proofs rejected. It does not describe side effects or failure modes, but for a single-field mutation it is substantively transparent.

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?

The description is front-loaded with purpose, then gives the precise use case, then behavioral/auth requirements. Every sentence earns its place; the length is justified by the lack of annotations and the security-sensitive nature of the tool.

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 output schema present and all three required params documented, the description covers purpose, merge semantics, alternative behavior, value echoing policy, and authorization. It is complete for an agent to select and call this tool correctly.

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 description coverage is 100%, so the schema already documents field, value, and dpop_token fully. The description adds useful context — secret rotation example and 'never echoed back' — but it doesn't add parameter syntax or format information beyond the schema, so baseline 3 is appropriate.

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?

Description opens with 'Add or update a single operator secret field,' naming an exact verb, resource, and scope. It then contrasts itself with re-delivering the whole bundle over Secure Courier, which clearly distinguishes it from authority_receive_credentials and authority_update_operator without needing to open schemas. This is a specific, differentiated purpose.

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 guidance is given: use it to rotate one secret (e.g., btcpay_api_key) without restating unchanged fields, where omitting fields in a full courier reply destroys them. It also states who may use it — operator only, not patrons — making the when/when-not boundary explicit.

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