Download attachment

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

Beyond the readOnlyHint annotation, the description adds the key behavioral detail that the file is returned base64-encoded. This is valuable context about the return format. However, it does not mention error handling, permissions, or size limits, but the annotations already cover the read-only nature.

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, front-loaded sentence followed by 'Read.' Every word earns its place; it is extremely efficient and easy to parse.

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, single-parameter, read-only tool with an output format specified, the description is nearly complete. It does not mention when to use the tool vs. alternatives, but given the straightforward nature and openWorldHint annotation, it is adequate.

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 has 100% coverage, documenting attachmentId as a GUID. The description merely restates 'by its id' without adding additional semantics. Baseline of 3 is appropriate since the schema already fully documents the parameter.

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 action ('Download'), the target resource ('an attachment file'), and the required input ('by its id'). It is specific enough to distinguish from sibling download tools like download_bound_book or download_multiple_sale_report, which target different resources.

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 is for downloading attachments by ID, but it does not explicitly state when to use this tool versus alternatives (e.g., other download tools) or provide any exclusions. The context is self-evident but lacks explicit guidance.

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