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

With no annotations, the description carries the full burden and does disclose the key operational facts: a per-call cost of 0.001 USDC via x402 with a PAYMENT-SIGNATURE header, or free access with an API key, plus that x402 clients auto-pay. It stops short of describing the return shape or what happens for an unlisted or unknown symbol.

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?

Purpose and usage lead, with access/payment details quarantined in a bracketed block so they do not dilute the front-loaded routing signal. The payment note is long but earns its place given zero annotation coverage of auth requirements.

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 one-parameter read tool with no output schema, the description supplies purpose, exclusion, and the full cost/auth model, which is the most important unknown. Remaining gaps (venue coverage, behavior on unknown symbols, result ordering) are modest but real.

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% and the single 'symbol' parameter is already documented with examples (BTC, ETH). The description only restates it as 'one specific token', adding no format or normalization guidance beyond the schema, so the baseline of 3 is appropriate.

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?

Names a specific resource (exchanges listing a given token) with the qualifier 'per-venue metadata', which tells the agent exactly what comes back. It also draws a line against price-lookup tools. It does not distinguish itself from the sibling list_exchanges, which an agent must infer covers the venue catalogue rather than a single token's listings.

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?

Explicit trigger condition: 'use it when the user asks where a token trades or which venues carry it', plus an explicit exclusion ('rather than for a price on any one of them'). No mention of when to prefer list_exchanges or get_market_data, so the routing vs. those siblings remains implicit.

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