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

Beyond the annotations, the description discloses meaningful behavioral details: files are downloaded into storage, Google Drive and Dropbox share links are converted automatically, the file must be publicly shared, and there is a 50 MB limit. These are useful execution traits not expressed in the structured metadata.

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 compact and well-structured: it opens with the primary action and output, then provides a clear when-not-to-use note, then adds the key constraints. Every sentence carries useful information without redundancy.

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 single-parameter tool, the description is complete: it explains the returned media_id, the reuse purpose, the relationship to schedule_post, supported link conversion, public-access requirement, and size limit. Even with no output schema, the agent knows what to expect.

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 schema already documents the url parameter well, including that it must be a direct https link and publicly reachable. The description adds extra semantic context—conversion of Google Drive/Dropbox share links and the 50 MB size restriction—which helps the agent choose appropriate input values.

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 action—'Download an image or video from a public link into sprkly and get a media_id back'—and clearly distinguishes it from the sibling sprkly_schedule_post, which accepts media URLs directly. This makes the tool's unique role immediately clear.

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 explicitly states when the tool is not needed ('You usually do NOT need this'), identifies the alternative tool, and gives the exact condition for using this tool: when the user needs one media_id reused across more than one post. This is exemplary usage guidance.

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