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

Goes well beyond the readOnlyHint/destructiveHint annotations: it discloses that filters are applied locally, explains the non-obvious source-derivation rule (declared source vs. slug-prefix inference), states that block markup is omitted from the response, and notes that `slug` switches to a single-pattern mode returning content and required_blocks.

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?

Core scope and the sibling exclusion are front-loaded and most sentences carry real information. However the final sentence is garbled/truncated ('Pass `slug` (a pattern `nam… Through Royally: its server marks it read-only...'), which costs readability.

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, but the description fully specifies the return shape ({ patterns: [{...}], total, total_pages, page, per_page }) and the alternate single-pattern return when `slug` is passed, so an agent knows what to expect.

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%, so the schema already documents all seven parameters including the source-derivation caveat and per_page bounds. The description restates these with examples rather than adding meaning beyond the structured fields; baseline 3 applies.

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+resource ('Lists the block patterns registered on the site') and immediately pins down scope: core/theme/plugin patterns from the editor's inserter, explicitly excluding synced patterns handled by wp_list_blocks. This lets an agent distinguish it from the large set of sibling list tools without opening a 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?

Names the alternative tool (wp_list_blocks) and the exact condition that selects it (synced patterns / reusable blocks). It does not give explicit guidance on when to use `slug` mode versus list mode or when filters are preferable, but the routing context is clearly stated.

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