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

No annotations are present, so the description carries the full burden; it adds useful behavioral context: the call is free/no credits required, and proof of npub ownership is needed to prevent enumeration of balances. It does not go further into response behavior or error conditions, but the output schema covers return shape.

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 the core purpose and keeps related context in short paragraphs. It is efficient overall, though the mistaken same-name alternative and slight repetition of the dpop-token requirement keep it from being perfectly clean.

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 only two parameters, no nesting, and an output schema, this is a low-complexity tool; the description provides purpose, cost, auth requirement, and a sibling distinction. The wrong sibling reference is the main completeness blemish; otherwise an agent has enough to call it 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 description need not add parameter-level detail; both npub and dpop_token are already well documented in the schema. The prose mentions proof of ownership and no-credit cost but adds no new semantic details beyond the schema.

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 first sentence names a specific action and resource ('Check a patron's credit balance at this operator'), and the description clearly distinguishes patron balance from the operator's own balance at the Authority. However, the alternative is referenced as 'authority_check_balance instead' — the same tool name as this one — which likely should be authority_check_authority_balance and prevents full sibling differentiation.

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?

It gives a clear use case and an explicit exclusion ('For the operator's own balance ... use authority_check_balance instead'), plus a prerequisite ('Proof of npub ownership is required'). But the named alternative is identical to this tool's name, making the routing instruction misleading and only recoverable by inferring the intended sibling.

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