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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutation profile is covered. The description adds the uniqueness precondition, but that same constraint is already stated in the schema's `before` description, so it adds little beyond structured data. Nothing is said about what happens when the precondition fails or whether the edit is atomic.

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?

Two short sentences, zero filler, with the core operation front-loaded and the matching precondition immediately after. Every clause earns its place.

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 four-parameter destructive mutation with no output schema, the description covers the core operation and precondition but omits failure behavior (what happens if `before` is missing or ambiguous), and gives no hint of the result an agent should expect after the edit.

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 75%, so the baseline is 3. The description's explanation of `before` (the exact current HTML passage, appearing exactly once) largely restates the schema, and it adds nothing about boardId or the format of `after`.

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 (change/replace) and resource (part of an HTML block) plus the mechanism (exact-passage replacement), which is far more informative than the title alone. It does not, however, differentiate itself from siblings like update_block or set_text, leaving the agent to infer which is appropriate.

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?

Usage is only implied: 'Change part of a block' suggests this is for surgical, partial edits rather than whole-block rewrites. No sibling is named as an alternative and there is no explicit when-not-to-use guidance, so the agent must reason about update_block vs edit_block vs set_text on its own.

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