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

The description is otherwise transparent: it discloses size/type/order constraints, url-vs-base64 source, replace vs append, and the no-auto-publish behavior. However, it states that replace mode 'deletes the ones it had,' which is an explicit destructive side effect, while annotations declare destructiveHint=false. That is a direct contradiction, so this dimension scores 1.

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 description is longer than the minimal case, but every block serves a purpose: constraints up front, exclusions, mode semantics, and follow-up workflow. It repeats some schema text, yet remains scannable with clear sentence boundaries.

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 mutation with no output schema, the description covers the required preconditions, input constraints, alternative sources, mode behavior, and post-call workflow (publish/schedule/list). The only contextual defect is the destructiveHint contradiction; otherwise an agent has enough to invoke it correctly.

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 already documents all four parameters in detail (100% coverage), so this is not a case where the description must compensate. It adds real value by stating hard constraints (JPG/PNG/WEBP, ≥200×200px, ≤8 MB, max 5 images, exactly one source per image) and clarifying that order determines the LinkedIn multi-image output.

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 first sentence uses a specific verb and resource ('attach... images to a ContentIn post') and adds the key precondition 'not published yet.' It also clarifies what it is not (it does not publish), which differentiates it from publish_post and schedule_post.

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 explicitly states unsupported types ('Video, GIFs, PDFs and document carousels are NOT supported and will be refused'), gives the required follow-up tools ('call publish_post or schedule_post afterwards'), and tells the agent to use list_posts to verify. It also explains when to choose replace vs append.

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