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

Annotations already declare non-readOnly, idempotent, non-destructive, open-world. The description adds real semantics beyond them: omitted fields retain their value, and new content replaces rather than appends. It also states the return payload. No auth/permission or failure behavior is disclosed, so not a 5.

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?

One tightly packed sentence with zero filler, front-loaded on the mutation itself, followed by the return value and endpoint. Every clause carries distinct information.

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 three-parameter mutation tool with no output schema, the description covers what changes, how omission is handled, and what is returned, while annotations carry the safety profile. Only permission and error-handling behavior are left unstated, a minor gap at this complexity.

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 a constraint the schema does not encode: at least one of title/content must be supplied even though only 'note' is required. It also clarifies replacement semantics that the schema's 'New content' wording leaves ambiguous.

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) and resource (a note's title and/or content), plus the transport endpoint POST /notes/{note}. An agent can distinguish this from notebook_create_note, notebook_get_note, and notebook_delete_note without opening any schema.

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 the operative invocation condition ('give at least one' of title/content) and frames the tool as a partial update of an existing note, which routes the agent away from create_note. It never names a sibling alternative or a when-not case explicitly, so it stops short of a 5.

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