FastMCP Documentation Search Server

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

No annotations are provided, so the description carries full burden for behavioral disclosure. 'Add two numbers' implies a mathematical operation but doesn't disclose any behavioral traits like error handling (e.g., overflow), performance characteristics, or side effects. For a tool with zero annotation coverage, this is insufficient.

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 perfectly concise at three words, front-loading the core functionality with zero wasted text. Every word earns its place by directly conveying the tool's purpose without unnecessary elaboration.

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 extreme simplicity (basic arithmetic operation), two straightforward parameters, and the presence of an output schema (which handles return value documentation), the description is reasonably complete. It clearly states what the tool does, though it lacks behavioral context that would be helpful given the absence of annotations.

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?

The description 'Add two numbers' implicitly defines the semantics of both parameters (a and b) as numbers to be added, which adds meaning beyond the schema's type-only documentation (integers). With 0% schema description coverage, the description fully compensates by clarifying what the parameters represent, though it doesn't specify format constraints beyond the implied numeric nature.

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 'Add two numbers' clearly states the verb ('Add') and resource ('two numbers'), making the purpose immediately understandable. It doesn't differentiate from siblings, but since sibling tools (hash_text, scrape_page, search_docs) perform completely different functions, differentiation isn't necessary here.

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. While the tool's purpose is simple and siblings are unrelated, there's no mention of context, prerequisites, or limitations. The agent must infer usage solely from the tool name and parameters.

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