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

No annotations are provided, so the description must carry the behavioral burden. It does disclose the output fields and the presence of a 'math_check' on line_items, which gives some behavior beyond a tautology. Still, it does not explain error handling, edge cases, whether the input is considered PDF versus raw text, or any side effects.

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 one compact sentence that is front-loaded with the core action and immediately lists the output fields. There is no filler, repetition, or unnecessary detail.

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 one-parameter, no-output-schema tool, the description covers the core action, the input type, and the expected output keys. It is slightly incomplete because the meaning of 'math_check' is not explained, but an agent can still invoke the tool correctly with reasonable confidence.

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 100%: the only parameter 'text' is already described as 'Invoice text or PDF extract.' The description adds no new parameter-level detail, so the schema does the heavy lifting and the description provides no extra compensation.

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 ('parse') and a specific resource ('invoice text') and lists the target fields (vendor, amount, due_date, line_items). It is clearly aligned with invoice parsing and distinct enough from generic siblings like extract_table or structure_text, though it does not explicitly name or contrast the alternatives.

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 the tool should be used when an agent has invoice text or PDF extracts to parse, and the parameter description reinforces this. However, it gives no explicit guidance about when not to use it, prerequisites, or which sibling tools might be more appropriate for different tasks.

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