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

Beyond the annotations (destructiveHint=true, non-idempotent), the description discloses that provider scopes, locks and credits apply, that confirmation is mandatory before execution, and that only one submission is allowed. This adds real operational context an agent needs, though it doesn't explain what gets destroyed or the return behavior.

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 clauses, front-loaded with the endpoint, with no filler. It is tight, though the leading endpoint path is more reference than value, keeping it from a 5.

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?

Annotations carry the safety profile and the schema is rich with a nested payload, so much is covered. However, for a destructive, open-world operation the description never explains the actual image-overlay behavior or its output, leaving a meaningful gap.

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 schema already documents account, confirm, payload and payload_file in detail. The description adds no parameter-level meaning beyond what the structured fields provide, so the baseline of 3 applies.

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 names the operation and endpoint, but 'POST /v5/tools/overlay_image' largely restates the tool name rather than stating what overlaying does (image onto a video?) or its effect. The surrounding text is metadata about provider scopes and confirmation rather than purpose. An agent gets the resource but no real verb semantics.

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?

It states a precondition ('Mandatory confirmation before provider execution; one submission only'), which is useful, but gives no when-to-use context and never contrasts with siblings like overlay_video or apply_color_filter. No alternatives or exclusions are offered.

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