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

With no annotations provided, the description fully owns behavioral disclosure. It reveals the merge behavior ('without touching the others'), side-effect context (courier reply destroys omitted fields), the never-echoed value, and authentication requirements (nsec-signed kind-27235 or cached dpop_token phrase). No contradictions exist.

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 composed of three short paragraphs, each with a distinct purpose: purpose, merge/contrast logic, and auth/restriction context. Every sentence adds essential information without redundancy or filler, matching the tool's complexity.

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?

Given the tool's mutating nature, restricted access, and the presence of an output schema, the description is fully complete. It covers the merge semantics, destruction caveat of alternatives, value privacy, and authentication requirements, leaving no critical contextual 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 description coverage is 100% for all three parameters, so the baseline is 3. The description adds a concrete example field name ('btcpay_api_key') and overall purpose, but does not need to compensate for schema gaps. It does not provide additional per-parameter semantics beyond what the schema already states.

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 opens with a specific verb and resource: 'Add or update a single operator secret field.' It clearly distinguishes from siblings like weather_update_patron_credential and weather_get_patron_credential_fields by emphasizing 'operator' and the field-level scope, reinforced by the analogy 'field-level counterpart to re-delivering the whole bundle.'

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 when to use: 'rotate one secret' without restating unchanged fields, contrasting with courier bundle delivery. It also gives exclusion criteria: 'RESTRICTED to the operator' and 'patron proofs are rejected,' preventing misuse by non-operators.

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