get_invoice

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

Annotations already indicate a safe read operation (readOnlyHint=true, destructiveHint=false, idempotentHint=true). The description adds no additional behavioral context beyond the basic action, so it does not contribute extra transparency but is consistent 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 a single short sentence, 'Fetch one invoice by ID,' that immediately conveys the action and resource. It is concise, front-loaded, and every word earns its place.

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 lookup tool with one parameter, annotations, and an output schema, the description is sufficient but not exhaustive. It could mention that search_invoices is for broader queries, but the current context is complete for the tool's simplicity.

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 description coverage is 0%, and the description does not compensate by explaining the parameter beyond 'by ID.' However, the parameter 'invoice_id' is self-explanatory and the schema provides integer type and required status, so the minimal semantics are adequate.

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 is specific: 'Fetch one invoice by ID.' It clearly states the verb (fetch), the resource (invoice), and the scope (by ID). This distinguishes it from sibling tools like 'search_invoices,' which implies searching rather than direct lookup.

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 implies usage when you have a specific invoice ID, but it does not explicitly state when to use this tool versus alternatives like 'search_invoices' for queries without an ID. No exclusions are provided, making guidance minimal.

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