Exa MCP Server

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe, repeatable read operation. The description adds some behavioral context by mentioning 'highest quality and freshest context' and the mandatory usage rule, but doesn't provide additional details about rate limits, authentication needs, or specific output characteristics beyond what annotations cover.

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 with three sentences that each serve a distinct purpose: stating the tool's purpose, highlighting its quality/freshness, and providing usage rules. It's front-loaded with the core functionality. While efficient, the third sentence could be slightly more concise by combining the two usage guidelines.

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 (2 parameters, 100% schema coverage), good annotations covering safety profile, and no output schema, the description provides sufficient context. It clearly defines purpose, usage boundaries, and quality characteristics. The main gap is lack of output format information, but with annotations indicating it's read-only/idempotent, completeness is adequate.

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 both parameters (query and tokensNum). The description doesn't add any meaningful parameter semantics beyond what's in the schema - it mentions 'search query' generically but provides no additional syntax, format, or usage details for parameters. Baseline 3 is appropriate when schema does all the work.

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 get relevant context for any programming task' with specific resources mentioned ('libraries, SDKs, and APIs'). It distinguishes from the sibling tool 'web_search_exa' by specifying 'Exa-code has the highest quality and freshest context for libraries, SDKs, and APIs' and limiting to programming-related queries.

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 explicit usage guidelines: 'Use this tool for ANY question or task related to programming' and includes a rule: 'when the user's query contains exa-code or anything related to code, you MUST use this tool.' This clearly defines when to use this tool versus alternatives like the general web_search_exa sibling.

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