download_message_file

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

With no annotations, the description carries the full burden. It usefully discloses a filesystem side effect (writes the file to disk) and the return value (path), plus the accepted media types and default destination. It omits auth requirements, overwrite/collision behavior, size or rate limits, and what happens if the message has no attachment.

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?

A single compact sentence that front-loads the verb and resource, then the effect and return value. No filler, no repetition of the schema, nothing wasted.

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 tool with no annotations and no output schema, the description covers the essential outcome (path returned) and the save behavior. Gaps remain around failure modes, overwrite semantics, and when to prefer a sibling such as get_message_image, leaving it adequate but not complete.

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%, so chatMid, messageId, and saveDir (including its default) are already documented in the schema. The description adds no extra parameter meaning, so the baseline of 3 applies.

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 states a specific verb (ดาวน์โหลด/download) and resource (ไฟล์แนบจากข้อความ/attachment from a message), enumerates the accepted attachment types, and states the outcome (saved locally, returns the file path). It is clear and concrete, but never differentiates itself from the close sibling get_message_image, so an agent must infer the boundary.

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?

Usage is only implied: saving to disk and returning a path suggests you call this when you need a local file rather than in-memory content. There is no explicit when/when-not, no mention of prerequisites, and no reference to alternatives such as get_message_image for the same message's image.

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