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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral context beyond these: it states the tool takes no payment, holds no key, and only reports which doors exist and are open. It also clarifies that 'wired but not open' channels are included, which is a non-obvious trait. No contradictions with annotations.

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 four sentences, each earning its place: opens with 'FREE' to set expectations, states the core function, enumerates the three channels with relevant audience details, and closes with a clarification that it's purely informational. No fluff, and the key purpose 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?

Given that an output schema exists (so return values are covered), the description provides all necessary context: what the tool does, the three channels, the free nature, and the fact it only reports status. It also mentions the /manifest endpoint for legal paths. No critical information is missing for an agent to correctly call this tool.

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 parameter 'path' is fully documented in the schema. The tool description does not add additional meaning about the parameter; it focuses on the channels and tool behavior. Per the baseline rule, when the schema covers the parameter fully and the description adds no new value, a score of 3 is appropriate.

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 clearly states the tool's purpose: to retrieve payment channels and their status for a listed endpoint. It uses a specific verb ('get'), a specific resource ('listed endpoint'), and explicitly names the three channels. Sibling tools (find_signal, get_official_record, verify_citation) are unrelated, so there's no confusion about which tool to use.

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 explains when to use the tool ('Ask how to pay for a listed endpoint') and provides context about omitted path behavior via the schema. It doesn't explicitly name alternatives or exclusion criteria, but given the sibling tools serve completely different purposes (signals, records, citations), the usage context is clear enough. It also directs users to /manifest?all=1 for legal paths, which is helpful.

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