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 valuable context about Exa-code's quality ('highest quality and freshest context') and scope ('libraries, SDKs, and APIs'), which enhances behavioral understanding beyond the annotations.

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 front-loaded with key information (purpose and quality) and includes a clear usage rule, all in three sentences. It's efficient with minimal waste, though the mandatory rule phrasing could be slightly more concise.

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 complexity (search with token control), rich annotations (read-only, idempotent, non-destructive), and 100% schema coverage, the description is mostly complete. It lacks details on output format or pagination, but with annotations covering safety and schema covering inputs, it provides sufficient context for effective use.

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 fully documents both parameters (query and tokensNum). The description doesn't add any parameter-specific semantics beyond what's in the schema, such as examples or usage tips for the parameters, so it meets 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's purpose with specific verbs ('Search and get relevant context') and resources ('programming task', 'libraries, SDKs, and APIs'), and explicitly distinguishes it from its sibling tool by emphasizing its specialization in code-related searches versus the more general 'web_search_exa'.

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 mandatory rule ('MUST use this tool') when the query contains code-related terms. It clearly differentiates when to use this tool versus alternatives by focusing on programming contexts.

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