Preview a result

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

Annotations already declare the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the description only needs to add context. It adds one genuinely useful operational fact — ffmpeg is required for video previews — but says nothing about latency, why idempotentHint is false for what appears to be a read, or whether job previews trigger a download as a side effect.

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?

Two short sentences, zero waste: the capability and scope come first, and the ffmpeg prerequisite follows. Nothing is repeated or padded.

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 low-complexity read tool with full schema coverage and no output schema, the description explains what comes back (a small preview image) and the environment prerequisite. It is nearly complete, though it leaves the nullable file/jobId pairing and the distinction from extract_frame unexplained.

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 every parameter (file, jobId, maxSize, position) is already documented in the schema. The description echoes the concepts ('one frame', 'small preview') but adds no format, default, or constraint detail beyond the schema, which is the expected baseline of 3.

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 ('Return a small preview image') plus the accepted inputs (local image/video, single frame, or finished job) and the intent ('check the result visually'). This is clearly distinguishable from job/generation tools, though it does not differentiate itself from the sibling axcel_extract_frame, which sounds like an overlapping capability.

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 clause 'so you can check the result visually' implies the use case (visual verification of output), and 'Needs ffmpeg for videos' is a useful precondition. However, there is no statement of when to prefer this over axcel_extract_frame or axcel_download_job, and no exclusions.

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