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

No annotations exist, so the description carries the burden. It usefully discloses the paid-call model (x402, $0.001/call, USDC on eip155:8453), which is real behavioral context, but it says nothing about the result shape (minutes/seconds), accuracy, or what happens for edge inputs like zero words.

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 short sentences, front-loaded with the core capability, then the pricing note. The em-dash price suffix is slightly awkward but every clause carries 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?

For a trivial two-parameter calculator with full schema coverage and no output schema, the description is nearly sufficient, but it leaves the return unit/format unspecified and its 'defaults to 200 wpm' claim conflicts with the required wpm parameter.

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 baseline is 3; the description's 'at any reading speed' adds little beyond the schema's own '200 = silent reading · 130 = read aloud' examples. It also claims a 200 wpm default while the schema marks wpm as required, which is a minor inconsistency that could mislead an agent into omitting a required field.

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 (estimate) and resource (reading time) plus the input basis (word count at any reading speed). An agent can distinguish this from the many sibling calculators and from dev_token_estimator without opening the schema.

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?

Usage is implied by the narrow single-purpose nature of the tool, but there is no explicit when-to-use guidance, no mention of when to prefer an alternative (e.g., token estimator or LLM cost calculator for LLM token budgeting), and no prerequisites.

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