Polymarket MCP Server

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

With no annotations, the description carries full burden. It discloses that it returns 404 for inactive tokens, which is useful behavioral context. However, it doesn't cover other aspects like rate limits, authentication needs, or what the spread output looks like (e.g., numeric value, format). This leaves some gaps for a tool with no annotation support.

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 sized and front-loaded with the core purpose. Every sentence adds value: the first states the action, the second provides source context, the third covers error behavior, and the fourth gives an example. It's efficient with minimal waste.

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 no annotations and no output schema, the description is incomplete. It explains the input source and error case but doesn't describe the return value (e.g., spread format, units). For a tool with 1 parameter and moderate complexity, this is adequate but leaves the agent guessing about the output, which is a significant 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 description coverage is 100%, so the schema already documents the token_id parameter. The description adds value by explaining that token_id should come from clobTokenIds and provides an example (token_id=clobTokenIds[0]), which clarifies semantics beyond the schema. This justifies a score above the baseline 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 tool computes spread from CLOB/book best bid/ask, which is a specific verb+resource combination. It distinguishes from siblings like get_batch_spreads (batch operation) and get_midpoint (different metric), though not explicitly. However, it doesn't fully differentiate from get_order_book which might provide similar data, keeping it at 4.

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 implied usage by mentioning source tokens from list_active_markets or get_market_details and noting 404 if no active CLOB. It doesn't explicitly state when to use this vs. alternatives like get_batch_spreads or get_order_book, nor does it provide exclusions, so it's adequate but with gaps.

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