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

With no annotations provided, the description carries the full burden and delivers: the worker downloads, stores in the project's asset bucket, returns { filename, sizeBytes, contentType }, and buffers in memory with a 16 MiB cap. It also discloses the server-side fetching mechanism and the constraint on public URLs. This is thorough, honest behavioral disclosure beyond what any annotation would typically supply.

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?

Each sentence in the description contributes essential information: the core purpose and uniqueness, the workflow and return value, the downstream usage of the filename, the URL constraints, and the memory cap. The description is front-loaded with the primary purpose and maintains a logical flow from action to result to subsequent steps, with no filler.

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?

Given the absence of annotations and output schema, the description is remarkably complete: it explains the entire operation lifecycle, return value shape, how to chain the result with sibling tools, how to find the overlay id, supported formats, URL constraints, and a critical size limitation. An agent has everything needed to invoke this tool correctly and integrate it into a workflow.

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 the baseline is 3. The description adds meaningful context beyond the schema: it explains the purpose of the returned filename and how to use it in subsequent overlay operations, reinforces the URL constraints, and clarifies the optional filename's default behavior. This elevates the value beyond what the schema alone provides.

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 the specific action ('Upload an audio track into a project by fetching a public http(s) URL server-side'), the exact resource, and explicitly distinguishes itself as 'the ONLY way' to get audio bytes into a project, contrasting with siblings that only reference filenames. This leaves no ambiguity about what the tool does or how it differs from related tools.

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 provides explicit guidance on when to use this tool, names the sibling tools it differs from (add_audio_overlay, update_audio_overlay), and explains the downstream workflow: pass the returned filename to add_audio_overlay or update_audio_overlay. It also specifies url requirements (direct, publicly-fetchable http(s), not auth-walled) and a size cap, making the usage context fully actionable.

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