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

Annotations already establish readOnly, idempotent, and non-destructive behavior. The description adds a valuable behavioral detail: 'The note content is automatically decrypted in the response', which informs the agent about response content and data sensitivity. This goes beyond the annotations.

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 short and front-loaded, but it repeats the exact same sentence in the opening paragraph and the 'When to use' section. This redundancy wastes space, preventing a higher score.

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 tool, the description covers purpose, prerequisite, and a key behavioral aspect (decryption). With no output schema, it could explain return structure, but the essential information is present and sufficient for correct invocation.

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?

With 100% schema description coverage, the schema already fully documents the note_token parameter. The description repeats the same definition without adding new meaning, so it meets the baseline but does not enhance it.

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 explicitly states 'Fetch a single note by its token', using a specific verb and resource. It distinguishes from fetch_notes by instructing to use fetch_notes first to obtain the token, clearly positioning this as the single-note retrieval tool.

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?

Provides clear context: 'Use fetch_notes first to get the note_token'. This gives a prerequisite and implies when to use this tool. However, it does not explicitly mention exclusions or alternative tools for different scenarios, stopping 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.