Polymarket MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It usefully adds that the tool may return a 404 error if the token lacks an active CLOB/order book, which is important context. However, it doesn't describe other behavioral aspects like rate limits, authentication needs, response format, or whether it's a read-only operation (though 'Get' implies reading). The description adds some value but leaves gaps.

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 appropriately concise with three sentences that each serve a purpose: stating the tool's function, providing source and error context, and giving an example. It's front-loaded with the core purpose. There's no wasted text, though it could be slightly more structured for clarity.

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 (single parameter, no output schema, no annotations), the description is somewhat complete but has gaps. It covers the purpose, parameter source, and an error condition, but doesn't explain the return value format or how the midpoint price is calculated. For a tool with no annotations or output schema, more behavioral and output context would be beneficial.

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?

The input schema has 100% description coverage, with the token_id parameter fully documented in the schema. The description adds minimal value beyond the schema by providing an example ('Example: token_id=clobTokenIds[0]') and mentioning the source of valid token IDs. This meets the baseline of 3 when schema coverage is high, but doesn't significantly enhance parameter understanding.

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 tool's purpose: 'Get midpoint price via CLOB /midpoint.' It specifies the verb ('Get') and resource ('midpoint price'), and mentions the data source ('CLOB'). However, it doesn't explicitly differentiate from sibling tools like 'get_current_price' or 'get_spread' that might provide similar price-related data.

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 provides some usage context by mentioning the source of token IDs ('Source: clobTokenIds from list_active_markets or get_market_details') and a condition for failure ('If token has no active CLOB/order book, returns 404'). However, it doesn't explicitly state when to use this tool versus alternatives like 'get_current_price' or 'get_spread', nor does it provide clear exclusions or prerequisites beyond the token ID requirement.

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