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

With no annotations, the description carries the burden and does well: it discloses that the call is free, that proof of npub ownership is required, and the security rationale (preventing registry-held balance enumeration). It stops short of describing what the returned balance structure contains, but an output schema exists to cover that.

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?

Three tight paragraphs: identity/scope first, disambiguation second, cost and auth last. Every sentence earns its place and the most important fact is front-loaded.

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?

An output schema exists, so return values need no prose. The description still supplies everything an agent needs to call this correctly: what is checked, how it differs from the sibling balance tool, that it is free, and the proof requirement.

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%, and the dpop_token schema itself is extensively documented (kind-27235, tag rules, freshness, nonce). The description adds no parameter-level meaning beyond the schema, so the baseline 3 applies.

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?

States a specific verb+resource+scope: 'Check a patron's credit balance at this operator.' It then defines what that balance actually is (credits purchased via Lightning for tool calls) and explicitly distinguishes it from the operator's own Authority balance, so an agent can tell it apart from beesknees_check_authority_balance without opening either schema.

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?

Names the alternative (authority_check_balance) and the exact condition that selects it ('the operator's own balance at the Authority'). It also states cost ('Free — no credits required') and the auth precondition, leaving nothing material to inference.

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