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

Beyond the annotations (readOnlyHint=true, idempotentHint=true), the description adds valuable behavioral context: no PII is returned, OAuth authentication is required, and the tool is read-only with no parameters. This directly informs agent expectations about side effects and prerequisites.

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?

Three concise sentences, each adding essential information: what the tool returns, what it excludes, and when to use it. The description is front-loaded with the core purpose and avoids redundancy with the annotations.

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 zero-parameter, read-only profile tool, this description is complete. It covers the return fields, the PII limitation, authentication requirements, and use cases. No output schema exists, but the field listing is sufficient for an agent to understand what the tool provides.

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 input schema has zero parameters, giving a baseline of 4. The description explicitly confirms 'takes no parameters', removing any ambiguity. With no parameters to define, there is nothing else to explain.

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 uses a specific verb ('Returns') and identifies a distinct resource ('authenticated user's Departi profile') with a concrete list of contents (nationality, tax residence, subscription tier, etc.). This clearly distinguishes it from the sibling tools, all of which are check/search/track operations rather than profile retrieval.

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 explicit usage context: 'Use to personalise the other tools' answers, or to answer "where do I stand right now"'. This gives an agent clear triggers for calling this tool. It does not explicitly name alternatives or say when not to use it, but the sibling list and the profile-specific purpose make the distinction obvious.

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