OpenRouter MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It describes a search/filter operation but doesn't mention whether this is a read-only query, if it requires authentication, rate limits, or what the output looks like. For a tool with 7 parameters and no annotations, this leaves significant behavioral 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 well-structured and appropriately sized: a brief purpose statement followed by a clear parameter list. Every sentence adds value, with no redundant information. It could be slightly more concise by integrating the purpose and parameters more fluidly, but it's efficiently presented.

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 has 7 parameters with 0% schema coverage and an output schema exists, the description does a good job covering parameter semantics. However, it lacks behavioral context (e.g., read-only nature, authentication needs) and usage guidelines relative to siblings. The output schema mitigates the need to explain return values, but overall completeness is moderate due to these gaps.

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 0%, so the description must compensate fully. It provides detailed explanations for all 7 parameters, adding meaning beyond the schema's titles and types (e.g., explaining 'max_input_price' as 'Max input price per 1M tokens, 0 = no limit' and 'requires_tools' as 'Only models supporting tool calling'). This effectively documents parameter purposes and constraints.

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: 'Search and filter OpenRouter models.' This specifies the verb ('search and filter') and resource ('OpenRouter models'), making it easy to understand what the tool does. However, it doesn't explicitly differentiate from sibling tools like 'list_models' or 'compare_models' beyond the filtering aspect mentioned.

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 no guidance on when to use this tool versus alternatives like 'list_models' or 'compare_models'. It lists parameters for filtering but doesn't explain scenarios where this search tool is preferred over a simple list or comparison, leaving the agent to infer usage based on parameter needs alone.

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