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

Annotations already declare readOnly/non-destructive/closed-world, so the safety bar is covered. The description adds real behavioral context beyond them: it returns a single paginated page of slugs with descriptions and tags, and also surfaces site sections that can be cloned, which an agent could not infer from the annotations alone.

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?

Front-loaded with the core action and return shape, then a compact clause per key filter. It is dense but appropriate for a 15-parameter tool, with only mild redundancy in re-listing the OR-filter and paging behavior already in the schema.

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 15-param read-only search with no output schema, the description covers result shape, paging, the two array filters, and a documentation pointer, which is enough to invoke correctly. Remaining gaps (sort/limit defaults, source vs preset) are minor and partly covered by the schema.

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 every parameter is already documented in the schema (q's phrase form, page default, OR-filter semantics for categories/styles are all present there). The description's parameter notes largely restate schema content, adding little new syntax or edge-case meaning, so 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 ('Search the block library') and immediately discloses the return shape (one page of slugs with descriptions and tags). It explicitly routes to get_block for full structure, letting an agent distinguish this shallow search from the deeper fetch without opening either 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 get_block as the path for full block structure and points to a get_style_reference guide, which gives some alternative awareness. However it never clarifies when to use this versus list_blocks or search_site_nodes, and offers no exclusions or prerequisites, leaving the sibling-choice mostly to inference.

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