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

Beyond the annotations (which already flag non-readonly, non-destructive, open-world), the description discloses real side effects: it enables a public preview link, may fetch external image URLs during import/rendering, and 'Never publishes'. That is meaningful context for a mutation tool, though the stray 'Returns JPEG' is cryptic.

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?

The guidance is front-loaded with the use case, then constraints, then follow-up behavior, with almost no filler. It is dense but each clause carries operational information; only the ambiguous 'Returns JPEG' fragment reads as waste.

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 10-parameter mutation tool with annotations and an output schema, the description covers selection, limits, formats, placement routing, and side effects adequately. The unexplained references/placementHint params and the unclear return mention are the only material gaps.

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 high (80%), so baseline is 3, and the description still adds value: it explains the slot-vs-array choice, the six-file total cap across both, accepted formats and the 10 MiB limit, and that slot names become richDocument src bindings. It omits mention of the references and placementHint parameters.

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 opening clause states a specific verb+resource ('adding images' to a draft) and explicitly carves out the boundary with update_post_draft for exact placement. However, it never differentiates from the sibling tool attach_media, which an agent would plausibly consider for the same task.

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?

'Use this when adding images without changing draft text' gives a clear selection condition, and 'Exact placement uses update_post_draft with richDocument slot bindings' names an alternative and when to prefer it. It stops short of a full when/when-not matrix (attach_media and create_media_upload are never referenced).

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