Fabits 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 mentions sending an OTP but fails to describe critical traits such as delivery method (e.g., SMS, email), rate limits, security implications, or response format. For a tool involving user communication and security, this lack of detail is a significant gap.

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 a single, efficient sentence that directly states the tool's purpose without unnecessary words. It is front-loaded and wastes no space, making it easy for an agent to parse quickly.

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 complexity of OTP sending in an investment context, no annotations, and no output schema, the description is incomplete. It omits details on behavior (e.g., delivery, errors), usage context, and return values, which are essential for an agent to invoke this tool correctly and handle responses.

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%, with clear documentation for all three parameters (user_id, phone_number, email). The description adds no additional meaning beyond the schema, such as explaining why all three are required or their interrelationships. However, the schema adequately covers parameter semantics, so the baseline score of 3 is appropriate.

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 action ('send transactional OTP') and the domain ('for investment'), which is specific and unambiguous. It distinguishes itself from sibling tools like 'fabits_request_otp' and 'fabits_verify_transactional_otp' by focusing on sending OTPs for transactional purposes, though it could be more explicit about the exact context (e.g., during investment processes).

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 'fabits_request_otp' or 'fabits_verify_transactional_otp'. It lacks context on prerequisites (e.g., user authentication), specific scenarios (e.g., after initiating an investment), or exclusions, leaving the agent to infer usage from the name and sibling tools alone.

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