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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real behavioral context beyond that: the empty-result semantics ('Empty means nothing places it yet'), the consequence framing (a submitted version replaces it everywhere), and a skill-doc precondition. It does not discuss pagination behavior, but the output schema covers the return shape.

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 purpose is front-loaded and the supporting sentences earn their place by explaining why to call it. Slightly dense with the trailing 'Rules:' line, but no wasted verbiage.

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 an output schema present and readOnly annotations provided, the description only needs to sell purpose and workflow. It covers scope, the empty case, and a precondition, leaving nothing important for the agent to infer before calling.

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 both parameters are well documented in the schema itself, including the reason the limit is 'a real bound rather than a page size.' The description adds no parameter-level detail, so the baseline of 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 and resource with precise scope: 'Where a block is PLACED: the templates using it as a header or footer, and the pages, posts and template zones whose content holds it.' This clearly distinguishes it from siblings like list-blocks (returns all blocks) or get-block-source (returns source for one block).

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 a clear trigger condition: 'Ask before editing a block — a submitted version replaces it everywhere.' The rules line further directs reading block-contract before the first call. It stops short of naming explicit alternative tools or when-not-to-use conditions, so a 4 rather than a 5.

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