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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false. The description usefully adds that existing text is replaced wholesale rather than appended or merged, which is real behavioral information. It says nothing about permissions, error conditions, or whether note metadata is preserved.

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 short sentence, front-loaded with the action and resource, with the parenthetical placed where it is useful. No wasted wording.

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 simple three-parameter mutation with no output schema, the description covers the core action and the noteId workflow. The unexplained userBookId and the lack of any note about overwrite consequences leave an agent with gaps before calling it.

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 0%, so the description must carry parameter meaning. It only explains noteId's source and leaves userBookId (why it is required alongside noteId) and the text field entirely unexplained beyond the schema's type and length limits.

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 ('Replaces the text of one note'), which separates it from add_note and delete_note among the siblings. It doesn't name those alternatives explicitly, but the operation is unambiguous.

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?

The parenthetical '(noteId from list_notes)' implies the discovery workflow before editing, giving some implied usage context. There is no explicit statement of when to use this instead of add_note, delete_note, or edit_highlight.

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