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

Annotations already cover readOnly/idempotent/non-destructive, so the bar is low, and the description clears it by adding the provenance caveat: it reports server-recorded settlements, not agent-authored claims. 'Free' also signals no cost, a useful trait not captured by annotations; only rate limits or freshness windows are absent.

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?

Two tight sentences, each earning its place: the first names the tool and its scope, the second disambiguates the data source. Nothing is padded or buried.

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?

For a zero-required-param read tool with no output schema, the definition covers scope, param behavior, and data provenance adequately. The one remaining gap is that the returned fields of a 'settlement summary' are never sketched, which an agent cannot infer from structured data.

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 schema already states 'Omit for service-wide settled spend.' The description's parameter guidance is essentially a restatement of the schema, adding no format, pattern, or example detail beyond what is structured.

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 combo ('read-only settlement summary') and clarifies the two scopes: one agent_id profile or service-wide settled x402 spend. It clearly is not a claims tool, which the second sentence spells out, though the word 'summary' still leaves the exact content abstract.

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 tells the agent when to supply agent_id versus omit it, which is genuine usage guidance for the single parameter. However, it names no alternative tool or condition under which another sibling (e.g. recover_pending, manage_purchase) would be preferred, so routing guidance is only partial.

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