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

Annotations flag destructiveHint=true and non-idempotent, and the description adds meaningful detail beyond that: header/footer targets *replace* the existing header/footer, and sourceNodeId "deep-clone[s] with fresh ids". `contentOverrides` applying final copy in the same call is also useful behavioral context, though permissions/return behavior are unstated.

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 its two modes, then the override/target semantics. Dense but every clause carries information; the trailing guide pointer is a minor bit of overhead but justified.

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 destructive, 9-parameter mutation tool with no output schema, the description covers the key modes, mutual exclusivity, replacement side effects, and override purpose. It stops short of stating permission requirements or failure/return behavior, but is largely sufficient to invoke correctly.

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 baseline is 3, but the description adds semantics the schema doesn't: contentOverrides is keyed by the block's lib_* ids, and target semantics (header replaces hdr_root, etc.) are clarified. This nudges it above 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?

States a concrete verb and resource ("Add a section") and enumerates the two mutually exclusive creation modes (stamp a library block via `slug` or deep-clone a page section via `sourceNodeId`). This clearly separates it from siblings like add_nodes/insert_node that lack the library/clone semantics.

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 explicit operating rules: "exactly one" of slug/sourceNodeId, target "header"/"footer" replaces the site header/footer, heroes are page sections, and points to get_style_reference({ topic: "blocks" }) for guidance. It does not, however, contrast this with sibling tools such as add_nodes or insert_node, so the agent must infer when this is preferred.

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