download_media

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

With no annotations, the description carries the full burden. It adds real behavioral context by naming the destination ('configured local directory') and source constraints (cached, allowlisted), but says nothing about overwrite behavior, failure modes, or required permissions for a filesystem-writing operation.

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 front-loaded sentence with the verb first and zero filler. Every clause (source constraints, destination) carries information.

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, so the description should state what is returned (e.g., a file path or bytes) and how failures behave, but it does neither. Combined with zero parameter documentation, an agent lacks enough to invoke this reliably.

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% for two required parameters, so the description must compensate. It only alludes vaguely to 'message' and 'directory' and never maps to chatId or messageId or explains their format, leaving both required params undocumented.

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 ('Download media') plus the scope constraint ('from a locally cached allowlisted message'), which clearly distinguishes it from the send_media sibling. It stops short of naming an alternative, so it is clear but not sibling-routing.

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 phrase 'locally cached allowlisted message' implies the precondition for use (the message must already be in the local cache and the chat/media allowlisted), but there is no explicit when-to-use versus send_media or when-not guidance. Usage is implied rather than stated.

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