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

Annotations already flag destructiveHint=true and non-idempotent, so the bar is lower; the description still adds the key behavioral detail that an omitted append replaces the existing body, plus the partial-update contract ('pass only what changes'). It does not warn about the dual role of title (identifier vs new value) or behavior on ambiguous title matches.

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?

Three tight sentences, front-loaded with the action, then addressing, then the one non-obvious flag. The 'add this to my notes' phrase earns its place by making the append path immediately recognizable.

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 5-parameter, zero-required, destructive mutation tool with no output schema, the description covers action, addressing, partial-update semantics and the append/replace branch. The remaining unknowns (ambiguous title resolution, field-preservation on omitted tags/title) are minor.

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; the description adds genuine meaning by clarifying that id or exact title are alternative addressing keys and by spelling out the append-vs-replace outcome for body. It leaves the title parameter's dual purpose (find it vs rename it) unresolved.

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 ('Change an existing note'), which clearly separates it from kb_create_note, kb_delete_note and the read-only siblings without naming them. It is not a tautology, but it never explicitly routes against the closest alternatives (create vs update, get vs update).

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 real operational guidance: address by id or exact title, pass only what changes, and use append=true for the 'add this to my notes' path versus replacement otherwise. No explicit when-not-to-use or sibling routing, 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.