weixin_send_file

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

With no annotations, the description carries the full burden of behavioral disclosure. It reveals that the source can be a local path or URL but says nothing about side effects, required permissions, or failure behavior, which is a significant gap for a send 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?

The description is a single sentence that front-loads the action and recipient. It avoids wasted words and is appropriately sized for the tool's simplicity.

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?

The tool has no output schema and no annotations, leaving the description to convey essential context. It omits any mention of prerequisites, authentication, or what distinguishes this from weixin_send_image, making it incomplete for safe invocation.

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 covers all four parameters with descriptions, achieving 100% coverage. The description only restates the 'source' property's type ('local file path or URL'), adding no new information beyond what the schema already provides, so it merits the baseline score.

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 a specific verb ('Send') and resource ('file attachment') to define the tool's core function. It clearly states what is sent and to whom, and distinguishes itself from sibling tools like weixin_send_image by mentioning generic file attachments. However, it doesn't explicitly contrast with siblings, so it's clear but not fully differentiated.

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 this tool is used for sending files as attachments, but it does not specify when to choose it over weixin_send_image or weixin_send. There are no exclusion criteria or alternative tool guidance, leaving the agent to infer usage context.

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