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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, and the phrase 'read-only, runs straight away' merely restates them without adding context. Nothing is said about what the counts are grouped by, whether zeros are included, or what the response looks like, and there is no output schema to cover that gap.

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?

One short sentence, front-loaded with the operation and resource. The trailing 'Through Royally: read-only, runs straight away' is redundant against the annotations and could be dropped, but the total length is not a burden.

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 trivial single-optional-parameter read, the description covers enough to invoke correctly, and the parameter is fully described in the schema. However, with no output schema present, the description should have said what the returned counts are keyed by (mime type, extension, etc.), which is the main thing an agent needs to interpret results.

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 description coverage is 100% and the single site_id parameter is fully documented with its enum value and resolved URL, so the schema carries the burden. The description adds no meaning beyond it (it never mentions site_id), which is the expected baseline for a one-parameter tool.

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 ('Get media counts') plus a qualifier ('by type'), which distinguishes it from sibling counting tools like wp_count_posts and wp_count_terms. The parenthetical site note is noise but the core purpose is unambiguous.

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 implies when the tool applies (you want aggregate media counts rather than a media listing such as wp_find_media or wp_get_media), but it never says so explicitly and offers no exclusions or alternative routing. The agent must infer the choice from the name alone.

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