position

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

Annotations already mark it read-only, non-destructive, and open-world. The description adds real value beyond that: `holding: null` is a normal response, a login session is required, and field mapping is only partly verified with `readFrom` naming actual mapped fields. No contradiction with annotations.

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 front-loaded with the core purpose, then covers the critical null case, the auth requirement, and data reliability caveats. Each sentence adds actionable information, and the structure follows the natural decision order for an agent.

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 one-parameter, read-only position lookup with no output schema, this description is thorough: it explains the main result fields, the special `null` case, the required session, and the reliability of the mapped data. An agent has enough context to call it correctly and interpret a normal null 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?

The single parameter is fully described in the schema (`IDX ticker, e.g. BBRI`) with 100% coverage, so the description does not need to add parameter details. It adds the context that the symbol is a single holding lookup, but that does not go beyond the schema's baseline.

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 states exactly what the tool returns for one symbol — quantity held, average price, and current value — and explicitly contrasts it with the sibling `portfolio`, calling out when it is cheaper. An agent can tell this apart from `portfolio` and other market 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 gives a clear selection rule: use this instead of `portfolio` when the question is about a single stock, and it notes the session prerequisite. It does not explicitly spell out when not to use it, but the single-symbol framing plus the sibling comparison provides sufficient context.

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