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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context beyond that: it states result limits ('up to 20 matches, newest first') and explains a real coverage restriction (only Royal MCP uploads and items read with wp_get_media_item). It does not add auth or rate-limit details, but the annotation coverage lowers that burden.

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 most important information is front-loaded: what it finds, how to query it, and when to use it. Some phrases repeat structured data ('site: demo.royalplugins.com' and 'read-only, runs straight away'), but the description remains reasonably tight overall.

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 read-only lookup tool with all-optional parameters, full schema coverage, and rich annotations, the description supplies everything an agent needs: purpose, lookup keys, when to use it, coverage limits, and result count/ordering. No output schema is missing in a way that leaves the caller guessing.

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 the baseline is 3, but the description adds meaningful nuance for sha256: it can be the hash of the file 'as uploaded or of the stored file.' That distinction is not fully captured by the schema's generic 'SHA-256 as 64 hexadecimal characters' line, so the description earns above the baseline.

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 description names a specific verb and resource ('Find media library items') and explicitly states the two lookup keys: source_url and SHA-256. It also distinguishes this from a generic media list by saying it covers files uploaded through Royal MCP and items read with wp_get_media_item.

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 gives a concrete when-to-use rule: 'Use it before uploading to check whether a file is already in the library.' That directly tells the agent when this tool is the right choice, and the scoping note about which files are covered makes the usage condition sharper.

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