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

With no annotations provided, the description carries the full burden. It discloses that this is a write to a sensitive credential vault, that proof of ownership is required, and that it is free. It also notes a non-destructive effect on other fields. It does not mention reversibility or failure behavior, but the output schema likely covers return details; overall this is solid for a delete 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 concise and front-loaded with the core action. Each sentence adds value: the action, the scope guarantee, cost, and the auth/sensitivity warning. No filler or repetition of schema details.

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 (3 required params, output schema present, many siblings), the description covers the essential purpose, scope, sensitivity, and prerequisite. It could add more about error cases or what happens if the field does not exist, but the output schema likely handles return semantics. Overall, it is sufficiently complete for typical usage.

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 provides 100% coverage, including detailed descriptions for npub, field, and dpop_token. The description adds no new parameter-level syntax or examples beyond what the schema already offers, so it stays at the baseline for good schema coverage.

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 ('Remove') and resource ('single patron credential field') and further clarifies scope by noting it deletes one field without affecting others. This clearly distinguishes it from sibling tools like update (brain_update_patron_credential), bulk delete (brain_forget_credentials), or read (brain_get_patron_credential_fields).

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 conveys clear context: this tool is for deleting a single credential field while preserving other fields. It also states proof of npub ownership is required, which signals a prerequisite. However, it does not explicitly name alternatives or state when not to use it (e.g., for deleting all credentials), so it misses the higher bar of explicit exclusions.

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