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

With no annotations, the description carries the full burden and does it well: it discloses that bitrate is chosen automatically, that a second re-encode may occur, the credit cost per output minute, async job_id behavior with polling via get_job, and that result links expire in 1 hour. These are exactly the operational traits (cost, latency, result lifetime) an agent cannot infer from the schema.

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?

Four tight sentences with zero filler; the core purpose is front-loaded and the operational details (cost, polling, expiry) follow in descending order of importance.

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?

There is no output schema and no annotations, yet the description covers the return path (job_id polling), the result lifetime, and the cost model. Nothing an agent needs to invoke this tool 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 description coverage is 100%, so the baseline is 3. The description adds the useful fact that bitrate is auto-selected (no such parameter exists), but says nothing about max_height, start_seconds, or duration_seconds semantics beyond what the schema already documents.

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?

States a specific verb and resource ('Shrink a video or audio file') plus the distinguishing goal ('to fit a size limit'), which separates it functionally from conversion (convert_media) and trimming (trim_media) siblings. An agent can tell what this tool produces without reading the 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?

Gives concrete triggering contexts ('8 MB for Discord or 25 MB for email'), which makes the when-to-use condition clear. It never names or excludes competing siblings such as convert_media or edit_video, so the routing guidance is implicit rather than explicit.

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