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

Annotations only mark it non-read-only/non-idempotent without explanation; the description supplies the reason — a $0.01 per-call charge — and the full x402 payment choreography (call unpaid to receive a PaymentRequired challenge, retry with payment in _meta["x402/payment"]). This is exactly the kind of cost/auth/retry context annotations cannot express, though the consequences of a failed or double payment are left unstated.

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?

Front-loaded with what the record contains, then the operational payment details and the HTTP fallback. Dense but every sentence carries actionable information; the payment paragraph is longer than ideal but is required for a paid tool.

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 no output schema, the description usefully enumerates the returned fields and fully explains how to pay over both MCP and HTTP. Remaining gaps — source_id format and failure behavior on unknown sources — are minor for a single-parameter read 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 0% for the single required source_id, so the schema gives the agent a bare string with no format. The description partially compensates by framing the parameter as identifying 'one data source', but it never states the expected identifier syntax or behavior on an unknown id.

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: returns the FULL Source Atlas record for one data source, and enumerates the record's contents (lawful route, licence basis + duties, cost, freshness, failure modes, alternatives). This distinguishes it in substance from atlas_route and atlas_changes, though neither sibling is named explicitly.

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?

There is no when-to-use guidance and no named alternatives: nothing tells the agent when to prefer atlas_record over atlas_route or atlas_changes, nor what prerequisites exist (e.g., needing a known source_id). The only procedural guidance given is about payment, not tool selection.

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