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

Goes well beyond the annotations: paid from USDF balance (never free credit), bounded by key/agent limits, max_price acts as a hard cap, failed non-2xx calls cost nothing, requires an API key, and returns the seller's answer plus a receipt. These are exactly the cost, auth, and failure semantics an agent needs before spending money.

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 core purpose well, but the body is a dense wall of semicolon-linked clauses with some redundancy ('what one call costs and nothing on top' vs 'costs nothing') that makes it harder to scan than it needs to be.

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 covers the return shape (seller's answer and receipt), cost/refund behavior, auth requirement, and the disabled-market error, leaving nothing essential for correct invocation.

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 the baseline is 3, but the description adds real meaning: max_price is a cap that 'nothing [is] on top' of, and it clarifies that the input payload is forwarded to the seller and governed by the seller's own policy. That routing/interpretation context is not in the 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?

States a specific verb and resource ("Calls a listing of the agents market by its id") and explicitly ties the id format to the sibling tool agents_market_search, so the agent can distinguish this from the search tool without opening either 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?

Makes the search-then-call workflow clear by referencing where the id comes from and notes the 503 market_calls_unarmed condition, giving real context for when the call will or won't work. It stops short of stating explicit exclusions against sibling tools like quote or x402_pay.

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