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

Annotations only cover the safety profile (readOnly, idempotent, non-destructive), leaving behavior to the description, which delivers: the 2097152-byte size ceiling, that non-image or oversized files return explanatory text plus a signed URL, and that a declared attachment type is never used to decide. These are real behavioral traits an agent cannot infer from the schema or 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?

Three tight sentences, front-loaded with the action and return type, then the argument mapping, then the fallback behavior. Every clause carries information; nothing is padding.

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?

There is no output schema, and the description compensates by describing both return branches (inline image vs text with a signed URL) and the condition that selects each. Combined with the argument contract and the get_ticket linkage, an agent has everything needed to call and interpret this tool.

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%, so the description must carry parameter meaning, and it does for cardId ('a card NUMBER or uuid', same as get_ticket) and attachmentIndex ('0-based index... default 0'). projectId is passed through unnamed and unexplained, leaving one of three parameters without added semantics.

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?

States a specific verb and resource ('Fetch one file attached to a board card') plus the return form ('as an inline image'). It also anchors itself to the sibling get_ticket by reusing its card identifier convention, so the agent can distinguish it from get_ticket, get_screenshot, and the other get_* siblings.

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 ties attachmentIndex to 'the 0-based index from get_ticket's trailing attachment list', which implicitly tells the agent to call get_ticket first and where the index comes from. It stops short of explicitly stating when not to use this tool or what to do when no attachment exists.

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