Wordstats

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

Annotations already declare readOnlyHint=true and destructiveHint=false, establishing this as a safe read operation. The description adds valuable context about the x402 pay-per-call payment model, cost ($0.001), and chain (eip155:8453), which is significant behavioral disclosure beyond what annotations provide. It doesn't describe the output format, but the output schema exists to cover that.

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?

The description is two sentences that front-load the core function, then add essential payment context. Every sentence earns its place — no filler, no repetition of schema content. Concise and efficient.

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 simple text-analysis tool with 100% schema coverage, an output schema present, and readOnly annotations declaring safety, the description covers the essential behavioral aspects: what it computes, the payment model, cost, chain, and the signing workflow. The two-call payment discovery flow is the key non-obvious behavior, and it's disclosed effectively.

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 parameters are well-documented structurally. The description adds value by explaining the use-case context for the text parameter ('a block of text') and clarifying the _payment parameter's role as a signed payment payload with the two-call retry flow. The _payment parameter's practical mechanics (sign locally, private key never leaves machine, first-call-then-retry flow) is meaningfully explained beyond schema.

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 clearly states the verb (Return) plus the specific resource (word count, character count, average word length) for a text input. It distinguishes from siblings by describing a text-analysis function that none of the sibling tools (qr, screenshot, dns, ocr, enrich) perform.

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 it processes 'a block of text' and mentions the pay-per-call nature with cost/pricing details. However, it doesn't explicitly say when to use vs alternatives or provide exclusions. The payment workflow is partially described (first call without _payment, then retry) but there's no explicit guidance on when this tool is preferable to other text tools.

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