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

With no annotations, the description carries full behavioral disclosure. It reveals instant acceptance up to 25%, that higher rates are 'reviewed, not refused', the earning rate (25% of settled orders), and the exact return value (ref-tagged URLs for check_domain and card checkout). This is rich context beyond the schema.

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?

Two sentences, front-loaded with the primary action ('Claim a referral code in a single call'), and each clause adds critical information: no human hurdle, returns URLs, earning model, and rate policy. No wasted words.

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?

For a 3-param tool with no output schema and no annotations, the description covers the core workflow, what the user receives, how earnings work, and the rate review policy. It's sufficiently complete for an agent to decide to use the tool and understand the result.

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 baseline is 3. The description adds meaning beyond the schema by explaining the rate parameter's behavior (auto-accept up to 25%, higher reviewed) and connecting the code to returned URLs, which enriches the static parameter types.

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 (claim a referral code in a single call) and the resource (referral code). It distinguishes itself from siblings by emphasizing 'no human review, no keys, no agent card,' making it a fast, self-service registration tool unlike the other tools.

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?

It provides clear context for when to use (instant single-call claim, no human review) but does not explicitly name alternatives or exclusions. The 'no human review' implies a contrast with a slower or more involved process, and the return URLs hint at integration with check_domain, but no direct 'use this instead of X' guidance is given.

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