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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is covered by structured data. The description's word 'whole' reinforces that existing content is fully overwritten rather than patched, which adds modest value, but it says nothing about permissions or side effects beyond that.

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?

A single front-loaded sentence with zero padding. It is efficient, though arguably terse to the point of under-specification.

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, 4-parameter mutation tool with 50% schema coverage and no output schema, one short sentence leaves too much unstated: no routing to or away from siblings, no guidance on the undocumented parameters, and no detail on the destructive overwrite.

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 50%, and the description adds little beyond the schema: 'whole HTML' loosely maps to the html field, which is already documented as 'The complete new HTML document'. The undocumented title and blockId parameters get no help from the description.

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 ('Replace') and resource ('the whole HTML of a block'), so the operation is unambiguous. It does not, however, distinguish itself from the nearby edit_block/add_block siblings, which an agent must choose between.

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?

There is no indication of when to use this tool versus edit_block (partial edits) or add_block (creation), nor any prerequisites or exclusions. The agent must infer the difference from the name alone.

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