Request a free Quant Data API key

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

The description discloses several behavioral traits beyond the annotations: the key is delivered only to the inbox and is never returned in the tool result, there is a shared daily quota of 10 successful calls, and a true marketing_opt_in stays pending until the recipient replies SUBSCRIBE. This adds substantial context that annotations (readOnlyHint=false, openWorldHint=true) do not convey.

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 well-structured and front-loaded with the core action. Every sentence adds value: no account required, coverage of data tools, key delivery mechanism, consent guidance, and pending status. It is appropriately detailed without redundancy.

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?

The description thoroughly covers prerequisites, side effects, quota, and parameter handling. However, it does not explicitly state what the tool result contains (only that the key is not returned). Given there is no output schema, a brief mention of the expected result would improve completeness, but it is not a major gap.

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%, but the description enriches parameter meaning. For email, it implies the user's consent is needed. For marketing_opt_in, it adds crucial semantics: defaults to false, not required, only set true with explicit consent, and pending behavior. This is significantly more than the schema's brief descriptions.

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 starts with a specific verb and resource: 'Send a free qd_ API key to an email address.' It clearly distinguishes this from sibling market-data tools by stating the key covers all four market-data tools and that no account or payment is required. The purpose is unambiguous and differentiated.

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 practical usage guidance: 'Ask the user for the email address before calling' and explicitly instructs when to set marketing_opt_in to true ('only when the email owner explicitly asks'). It also clarifies that marketing_opt_in defaults to false and is not required. While it does not explicitly name alternatives, the context of siblings makes the appropriate scenario clear.

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