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

The readOnlyHint annotation already establishes that this is a safe read operation. The description adds meaningful behavioral context by listing what the response contains and explaining where the required id originates, which helps an agent understand the expected call pattern.

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?

The description is two short sentences with no wasted language. The key information, what the tool returns and where the id comes from, is front-loaded and immediately actionable.

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 single-parameter read tool with no output schema, the description is complete enough: it identifies the resource, the return contents, the id source, and the underlying endpoint. An agent has what it needs to invoke the tool correctly.

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 the single id parameter is fully documented in the schema. The description adds provenance by stating that the id comes from search or autocomplete, giving the agent practical guidance beyond the schema's type and range constraints.

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?

The description states a specific resource and access pattern: one note by id, including the returned fields (text, type, linked contacts and properties). It distinguishes itself from search/list tools by emphasizing a single note retrieved by id, though it does not explicitly name a sibling alternative.

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?

It implies when to use the tool by saying the id comes from a search or autocomplete, which gives useful context. However, it does not explicitly name alternatives such as rex_search_notes or state when not to use this tool, leaving usage guidance mostly implied.

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