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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, lowering the bar, but the description adds real value beyond them: signedUrl has a 6 h lifetime, publicUrl is stable for timeline ops, and the call is free. Minor tension in calling a finalize-style step 'readOnly', but not a direct contradiction.

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?

Front-loaded with purpose, then key formats, then return semantics, then cost. Every clause carries information an agent needs; 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?

Despite an output schema already existing, the description covers the non-obvious return traits (URL stability, expiry), the accepted input variants, and cost. Nothing needed to call it correctly is missing.

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, but the description adds accepted key formats (api-uploads/ and api-imports/ prefixes) and their provenance (create_upload / import_asset_from_url) beyond what the schema's 'agent-media/...' example states.

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?

Specific verb+resource ('Confirm an upload') with scope and an explicit statement of what it accepts and returns. An agent can distinguish it from create_upload, media_reserve_upload, and import_asset_from_url without opening a schema.

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?

Explains the flow context – pass the slot key/mediaId, and notes that api-uploads/ and api-imports/ keys from create_upload / import_asset_from_url also work, so the agent knows where keys originate. It stops short of explicitly naming when NOT to use it or naming an alternative tool.

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