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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false; the description adds genuinely new context — that writes are all-or-nothing (nothing is written if any key is refused) and that scope is limited to the caller's merchant. It doesn't say whether overwritten values are recoverable or how errors are surfaced, which matters for a destructive mutation.

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 sentences, zero filler; the scope constraint is front-loaded and the sibling hand-off follows immediately. Every clause carries information an agent needs.

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 destructive, no-output-schema mutation the description covers the key gaps (allowed keys, atomicity, tenant scoping, alternative tool), but omits the identifier-selection rule and any indication of what a successful call returns. Adequate but with a visible seam around the `image_id`/`image_uuid` pair.

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 0% and the required `updates` parameter is a free-form nested object, so the description's enumeration of allowed keys (title, description, language, keywords) is the only documentation of its contents — real added value. However, the relationship between `image_id` and `image_uuid` (either/or, precedence, whether at least one is required) is left unexplained in both schema and description.

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 (update image metadata), enumerates the exact keys it touches (title, description, language, keywords), and names the identifier fields used for lookup. It also distinguishes itself from the closely-related render_image, so an agent can tell the two apart without opening either 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?

"Update only the metadata" plus "any other key is refused and nothing is written" sets a clear boundary on when this tool applies, and "The editor document and output are changed with render_image" routes the agent to the correct alternative for non-metadata edits. It never states the inverse condition ("use render_image when you want to change the rendered output") in one explicit sentence, so a 4 rather than a 5.

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