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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, and the description's 'read-only, runs straight away' merely restates them. What it does add beyond annotations is a precise inventory of what is returned (dimensions, sha256, downloaded_from, source_sha256), which matters because there is no output schema, but it says nothing about behavior on a missing or inaccessible ID.

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?

Purpose is front-loaded in the first clause, followed by a dense but justified field list that substitutes for the absent output schema. The trailing 'Through Royally: read-only, runs straight away' is boilerplate duplicating annotations and could be dropped.

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?

With one required param, no output schema and safety already covered by annotations, the description carries the right extra weight by enumerating the returned fields including scaled-image and upload-provenance extras. It falls short only on failure behavior and on any tie-break against the near-duplicate media tools.

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 only 50%: site_id has an enum description, while id is a bare integer. The description's 'by ID' clarifies that id is a media item identifier rather than a post or user ID, but adds no format or validity detail, and site_id is never addressed beyond the parenthetical site note.

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 with a clear cardinality constraint: 'Get one media item by ID.' The 'one ... by ID' phrasing implicitly separates it from list-style siblings like wp_get_media, wp_find_media and wp_count_media, but no sibling is named, so the agent must infer the boundary.

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?

The description never says when to use this instead of wp_find_media (presumably the search-then-fetch path) or the other vendor's get-media tools in the sibling list. There is only implied usage from 'by ID' — no prerequisites, no when-not conditions, no routing to an alternative.

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