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

Annotations already signal a mutating external operation (readOnlyHint=false, openWorldHint=true). The description adds useful behavioral context beyond annotations: the beta status, X's JPEG/PNG-only limitation, unsupported input methods, and a failure reporting path. It does not detail duplicate creation or auth requirements, but it does not contradict the annotations.

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 six short, dense sentences with the core operation front-loaded. Every sentence earns its place: beta warning, destination platforms, accepted source types, X restriction, fallback behavior, unsupported inputs, and error routing. There is no filler or redundant repetition of schema content.

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 complex 9-parameter upload tool with no output schema, the description covers the main invocation paths, source selection, platform destinations, and important limitations; the rich schema descriptions handle parameter details. It is slightly incomplete regarding what the tool returns after request_upload_url or a successful upload, but the core calling contract is clear.

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 coverage is 100%, so parameters are already well documented in the schema. The description adds semantic constraints not present in the schema: base64/local paths are invalid, X supports only JPEG/PNG, and a requested upload URL substitutes when no attachment or public URL exists. This lifts it above the baseline.

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 opens with a specific verb and resource: 'Upload one file to Meta, Google, TikTok, LinkedIn, X, or Studio.' It also enumerates the supported source types and includes a platform-specific format caveat, making the tool's purpose unmistakable and distinguishable from sibling tools like adkit_library or adkit_studio.

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?

It provides explicit when-to-use guidance: attach a file, use a public HTTPS URL, use a completed temporary upload, or request an upload URL when no attachment/public URL exists. It also states clear exclusions ('Base64 payloads and local file paths are not accepted') and routes failures to adkit_feedback.

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