watermark_media

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

Annotations already declare idempotentHint=true and destructiveHint=false, and the description adds genuinely non-redundant behavior: it consumes credits, defaults to async, sync can yield a 202 job, and it requires the watermarks:embed scope. It omits failure modes and whether output is written to output_path vs returned inline, but the credit and auth-scope disclosures are real added value.

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?

Three short sentences with zero filler, and the core purpose is front-loaded ahead of cost, mode, and scope details. Every clause carries distinct information.

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 9-parameter mutation tool with nested free-form data, 11% schema description coverage and no output schema, the description is too thin. It never explains how watermark content is supplied or where results land, which is exactly the gap the description should close.

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 only 11% — essentially just idempotency_key — across 9 parameters with 4 required. The description mentions mode values only (which the schema's enum and default already convey) and says nothing about media, input_path, output_path, storage_key, storage_destination_id, webhook_id, or the free-form data object that drives the watermark content. It fails to compensate for the coverage gap.

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 (watermark) plus resource and media scope (image, PDF, video) in a single front-loaded clause. None of the sibling tools perform watermarking, so an agent can route to it unambiguously without opening 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 partial operational context: credit cost and the sync/async default with the note that sync may return a 202 job. It does not say when an agent should prefer sync vs async, nor when to pick this tool over detect_media/store_asset in a pipeline, so usage is only implied.

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