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

No annotations provided, so description carries full burden. It discloses the paid nature, cost per call, payment mechanism (x402 on Base), and the two-step process. Missing explicit statement of read-only behavior, but the purpose implies no side effects.

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?

Single clear sentence for purpose, followed by a compact note on payment. No redundant words, front-loaded with key information, every sentence earns its place.

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?

Description covers purpose, payment, and key constraints. Missing output format details (no output schema), but for a historical weather tool with clear parameter descriptions and payment guidance, it is fairly complete.

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 coverage is 100%, so schema documents all parameters well. The description adds value by explaining the payment_signature parameter's two-call process and the 90-day range constraint already in schema, but this extra context improves usability.

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 uses a specific verb ('get_weather_history') and resource ('historical daily weather for any location worldwide'), listing data points (temperature, precipitation, wind speed, conditions). It clearly distinguishes from sibling tools like 'get_forecast' (future) and others.

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 the payment flow: first call without payment_signature returns payment requirements, then retry with signature. It implies when to use (when historical data needed) but does not explicitly state when not to use or compare to alternatives like 'get_forecast'.

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