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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the underlying REST endpoint (GET /rest/notes/{id}), which reinforces the read semantics, but says nothing about hydration behavior or error cases when the id does not exist.

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, front-loaded with the action. The REST path second sentence is low-value for an agent that never issues raw HTTP calls, so it is mild filler rather than waste.

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 low-complexity single-record read with full parameter documentation and a readOnly annotation, the description is sufficient. With no output schema, the note's return shape is unexplained, but that is a minor gap for a standard entity fetch.

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 100% — both 'id' and 'depth' (including the 0-2 hydration range) are documented in the schema. The description adds nothing beyond it, so the baseline 3 applies.

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+resource+scope: 'Get a single note by id,' which an agent can distinguish from twenty_list_notes. It does not name a sibling explicitly, but the singular 'single note by id' framing makes the boundary obvious.

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: use this when you have a note id and want one record. There is no explicit when/when-not guidance or pointer to twenty_list_notes for lookup-by-filter, which is the main alternative an agent would weigh.

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