wechat_send_image

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

With no annotations, the description carries the full burden. It discloses a key behavioral trait: the caption is sent as a separate text message before the image. However, it does not mention other relevant behaviors such as error handling, whether the operation requires login, or what the return value/response indicates, leaving gaps for an agent.

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 two short sentences, front-loaded with the main purpose, and contains no filler or redundant information. It earns its place by adding the useful caption-ordering detail without extra wordiness.

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 send tool with 3 parameters, no output schema, and no annotations, the description gives the essential behavior and a notable quirk, but it lacks information about error conditions, response format, or any prerequisites beyond the parameter list. It is minimally viable but not fully 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 only 33% (only imagePath is described). The description adds meaning for caption (sent separately) and reinforces that imagePath is a local file, but it does not address userId at all, and it does not fully compensate for the low coverage of the other parameters. More explicit parameter explanations are needed.

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 the specific verb 'Send' with the resource 'a local image file', clearly distinguishing it from sibling tools like wechat_send_text and wechat_send_file. The added note about caption being sent separately further clarifies the tool's unique behavior.

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 usage by stating the tool sends a local image file, but it does not explicitly contrast with wechat_send_text or wechat_send_file, nor does it state when this should be preferred. The usage context is only implied through the type of file, not explicitly guided.

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