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

With no annotations provided, the description carries the full burden of behavioral disclosure. It clearly states values are never exposed, the operation is free, proof of npub ownership is required, the field list itself is sensitive, and delivered_at may be null for older vaulted secrets. This gives an agent essential behavior and safety context beyond a simple read operation.

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 compact and front-loaded with the core message ('List stored patron credential field names (not values)'), followed by concise details about return data, cost, and authentication. Every sentence contributes meaningful information without redundancy.

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 moderate complexity, the presence of an output schema, and the lack of annotations, the description covers all essential aspects: what it lists, what it does not return, cost, auth requirement, and why the data is sensitive. Nothing an agent needs to call it correctly is missing.

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 input schema already provides 100% coverage with detailed parameter descriptions, so the baseline is 3. The description adds context about npub ownership and sensitivity, but it does not need to explain parameter syntax further because the schema is thorough.

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 uses a specific verb ('List') with a clear resource ('stored patron credential field names') and explicitly distinguishes names from values. It also states the tool's purpose: verifying which fields are configured and their age, which separates it from sibling mutation tools like update_patron_credential and delete_patron_credential.

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?

The description gives clear context for when to use the tool: 'use this to verify which fields are configured and how old each one is.' It does not explicitly mention alternatives or exclusion conditions, but its use case is specific enough that an agent can decide when it applies.

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