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

Goes well beyond the readOnly/openWorld annotations by disclosing the cost model ($0.02/call via x402, key paths, free trial limited to 1/day over MCP only), the ranking methodology and window, and an integrity guarantee (formula published, positions not sold). Auth and rate-limit behavior are explicit.

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-loads the decision question, then layers pricing, method, and integrity in a compact block with no filler sentences. It is slightly dense and could separate the payment mechanics from the ranking explanation, but nothing is wasted.

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 compensates reasonably by stating what is returned ('every input so the score can be checked') and by covering pricing, auth, trial limits, and valid categories. A little more on the return shape (ordering, per-provider fields) would fully close the gap.

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, but the description adds real meaning: it enumerates the valid category values with alias acceptance and explains the api_key trade-off (omit for free trial or to surface x402 payment details). This goes beyond the schema's example-only category description.

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 with the exact ranking inputs: reliability (7-day probe success share), reputation (unique buyers), and price. An agent can distinguish this from siblings like get_category_detail or get_provider_revenue because the description names the composite decision it produces ('which provider should my agent pick').

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?

Frames the use case directly as a selection question and clarifies the payment routing (x402 vs Builder/Pro key vs 1 free MCP trial/day), which is real context for deciding whether to call it. It stops short of naming alternatives or exclusions (e.g., when to prefer verify_before_pay or get_category_detail), so it does not reach a 5.

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