Polymarket MCP Server

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

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions the return format ('Returns market data or error per slug') and provides an example, but doesn't cover important behavioral aspects like whether this is a read-only operation, rate limits, authentication requirements, error handling specifics, or what 'market data' includes. For a tool with no annotations, this leaves significant 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 core function, providing source context, and giving an example. It's front-loaded with the main purpose. There's minimal waste, though the example could be slightly more informative.

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 provides basic context but leaves significant gaps. It covers the purpose and parameter usage but doesn't explain what 'market data' includes in the return, error conditions beyond 'error per slug', or behavioral constraints. For a comparison tool with no structured output documentation, this is minimally adequate but incomplete.

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 fully documents the single parameter (market_slugs with type, constraints, and description). The description adds minimal value beyond the schema - it mentions the parameter in the example but doesn't provide additional semantic context about what constitutes valid slugs or how comparison works. Baseline 3 is appropriate when schema does the heavy lifting.

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: 'Compare multiple markets by slug' specifies the verb (compare) and resource (markets). It distinguishes from siblings like get_market_by_slug (single market) and list_markets (listing without comparison), but doesn't explicitly differentiate from all siblings like filter_markets_by_category. The description is specific but lacks full sibling differentiation.

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 guidance by mentioning 'Source: slugs from search_markets/list_markets' which implies when to use this tool (after obtaining slugs from those tools). However, it doesn't explicitly state when NOT to use it or name specific alternatives for different use cases. The guidance is implied rather than explicit.

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