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

Annotations already declare write/non-idempotent/openWorld, but the description adds real behavioral context: an account is created and a 6-digit code is emailed, and registration only completes via a follow-up call to mcp_verify. It goes further by spelling out the legal meaning of accept_terms. It stops short of noting duplicate-registration behavior or rate limits, so not a full 5.

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?

Front-loads purpose, then the flow, then the legal clause, then a concrete example. The legal paragraph is verbose but justified for a terms-acceptance field, so most sentences earn their place.

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?

An output schema exists, so return values need not be explained, and the description fully covers the multi-step registration flow and the required terms acceptance. An agent has everything needed to invoke it correctly.

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 coverage is 100%, so the baseline is 3, but the description adds meaning beyond the schema for accept_terms by explaining it confirms acceptance of the Terms on behalf of the operator, citing specific sections. The inline example also clarifies positional usage.

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?

States a specific verb+resource ('Register for an Ohmyfin API key') with the downstream purpose ('to use paid tools'). It distinguishes itself from the sibling mcp_verify by explicitly describing the registration step versus the completion step.

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?

Explicitly says when to call this (to obtain an API key for paid tools) and routes the agent to the next step: call mcp_verify after receiving the 6-digit code. The sequencing and the alternative tool are both named, leaving nothing to inference.

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