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

Annotations already declare readOnlyHint=true, so the agent knows this is a safe read operation. The description adds context about what is returned (market id, slug, window, status, timing) and how to chain the result with other tools, but does not disclose any additional behavioral traits such as pagination behavior or rate limits beyond what the schema already covers. It provides reasonable context beyond the annotations without contradiction.

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: the first states the core function and output, the second explains how to use the output. It is front-loaded with the most important information and contains zero filler or repetition. Every sentence earns its place.

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?

Given the tool's moderate complexity (7 optional parameters, no output schema), the description provides the essential use case and return concept, but it does not fully specify the structure of the result beyond naming fields, nor does it mention default behavior like the default coin. However, the input schema covers parameter details, and the description's guidance for chaining with other tools is useful. It is mostly complete for a search tool with rich schema documentation.

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 description coverage is 100%, so all 7 parameters are fully documented in the input schema with detailed descriptions, defaults, enums, and format guidance. The tool description does not need to repeat this and does not add extra parameter meaning. This matches the baseline expectation of 3.

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 'List' with a specific resource: Polymarket up/down crypto prediction markets for a coin. It distinguishes itself from sibling tools like polymarket_all_markets by the 'for a coin' scope, and it lists the key return fields (id, slug, window, status, timing), leaving no ambiguity about the tool's purpose.

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 offers a clear context for when to use the tool — to list markets for a coin — and even guides the next step by suggesting using the returned id/slug with polymarket_get_market or polymarket_get_snapshots. However, it does not explicitly state when not to use it or mention alternatives like polymarket_all_markets for broader searches, so the exclusion/alternative guidance is missing.

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