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

The description adds substantial behavior beyond the read-only and idempotent annotations: latency, cost, free-quota terms, 404 non-charge behavior, and a security warning to treat returned strings as untrusted data. These details directly affect invocation planning and downstream handling.

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 purpose and inputs, then operational details and safety notes in a compact, well-ordered paragraph. Every sentence contributes actionable information.

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 still summarizes the return shape (record plus dated presence rows and price-change points). It also covers inputs, latency, pricing, quota, 404 handling, and data-trust caveats, making it complete for this read-only history 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%, and the schema already documents each of the three optional parameters. The description usefully consolidates the `source`+`id` versus `url` selection logic, but does not add syntax or constraints beyond what the schema provides, so 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 and resource: retrieval of presence and price history for ONE indexed record. The scope ('ONE indexed record') distinguishes it from bulk-query or scan siblings, so an agent can identify it without opening other tool definitions.

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?

Clearly explains when the tool applies and how to identify the target record via `source`+`id` or `url`. It does not explicitly name alternative tools for bulk history or general agent-index queries, so it falls short of full when/when-not routing.

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