Get stock entry

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

Annotations already declare the tool as read-only, idempotent, and non-destructive, so the description does not need to restate that. It adds valuable behavioral context: returns all fields by default, allows narrowing via 'fields', and crucially discloses that monetary values are integers in cents (150 = 1.50 EUR). This goes beyond annotations and helps prevent misinterpretation.

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 four sentences, each earning its place: purpose, usage guideline, field-narrowing tip, and currency caveat. It is front-loaded with the primary action and contains no redundant information.

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 simple read-only tool with good schema coverage and no output schema, the description is complete. It explains what the tool does, when to use it, how to filter fields, and highlights a critical unit conversion. It also directs the user to the sibling list tool when appropriate, ensuring the agent has enough context to select and invoke 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?

The input schema already covers all three parameters with descriptions, so the baseline is 3. The description adds extra meaning by explaining the effect of the 'fields' parameter ('narrow the response') and the cost implication ('Fewer fields = less context used'). It also provides the important units for monetary values, which influences how parameters and responses should be interpreted.

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 tool fetches one stock entry by its numeric ID, which is a specific verb+resource. It explicitly distinguishes itself from the sibling list tool by stating that list should be used first if only a name or number is known.

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 direct usage guidance: use this tool when you have the numeric easybill ID, and use easybill_list_stock_entries first if you only know a name or number. It also explains how to use the 'fields' parameter to narrow the response, which is actionable.

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