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

Annotations already cover readOnly/destructive/openWorld, so the safety profile is known. The description adds real context beyond that: the scope difference between calls with and without workspaceId, and the meaning of the per-item 'source' field ('library' vs 'upload').

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?

Four short sentences, front-loaded with the core purpose and then the branching semantics; no filler. Slightly dense in the middle sentences but every clause carries 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?

No output schema exists, and the description compensates by describing the returned item's 'source' field and the two id families. Pagination is left to the schema's page/pageSize descriptions, which is reasonable for a 4-parameter read tool.

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 100%, so baseline is 3, but the description adds cross-tool meaning beyond the per-parameter text: it explains the concrete result-set consequence of passing workspaceId and confirms that both id kinds are accepted downstream by create_post.

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 ('List media that can be attached to posts') and implicitly distinguishes itself from upload_media_from_base64/upload_media_from_url/delete_media in the sibling set. An agent can tell what this returns 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 explicit conditional guidance: include workspaceId to get the dashboard library plus API/MCP uploads, omit it to get only API/MCP uploads. It also notes both id kinds are valid in create_post, which frames when this tool is useful. It does not name a sibling alternative explicitly, so it stops short of 5.

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