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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds useful context beyond them: the sources patterns come from, and the cost warning that include_content markup "can be large". It doesn't cover pagination behavior or result ordering.

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?

Three short sentences: what it returns, how to filter, and the opt-in expensive flag last. Every sentence carries information an agent needs; nothing is padding.

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 no output schema, the description enumerates the returned fields (name, title, categories, description) and the extra payload when opted in. Combined with full schema coverage and read-only annotations, an agent has everything needed to call it correctly and interpret the response.

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% and describes all four parameters with defaults, so baseline is 3. The description earns a bump by explaining the purpose of include_content (raw block markup that can be planted into a post) rather than just restating its type, though it adds nothing for limit or the category slug format beyond the schema.

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 the block patterns available on the site") and explains what a pattern is ("ready-made layouts from WordPress, the theme and plugins"), plus the fields returned. It also distinguishes itself from the post-mutation siblings by noting the markup is consumed by Update post or Edit post text, so an agent knows this is the read/discovery side.

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 clear conditional guidance: filter by search text or category, and set include_content only when the block markup is actually needed. It names the downstream tools for the retrieved markup, which is a strong routing hint. It stops short of explicit when-not-to-use guidance (e.g. versus wp_write_blocks).

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