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

Annotations already mark the operation as idempotent and non-destructive, and the description adds useful context by stating that existing tags are preserved. This prevents an agent from assuming the tags parameter replaces the full tag list, which is valuable 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?

Two short sentences deliver the core action and the most important behavioral caveat with no filler. The description is front-loaded and every sentence earns its place.

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 two-parameter tool with an output schema and safety-related annotations, the description is mostly complete. The only notable gap is the absence of any statement about errors or preconditions, such as whether the note must exist before tagging.

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?

The input schema has 0% description coverage, so the description must carry the semantic weight. It does convey that 'id' identifies the note and 'tags' are the tags to add, and the 'kept' clause disambiguates the merge behavior. However, it omits details like tag naming constraints, duplicate handling, and whether tags must already exist.

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 verb and resource: 'Add tags to a note.' It also clarifies the merge behavior ('Tags already on the note are kept'), which distinguishes it from tools like untag_note. The purpose is unambiguous.

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?

The usage is implied: use this when you want to add tags to a note rather than remove or replace them. However, it does not explicitly mention alternatives like untag_note or explain when not to use this tool, so the guidance is only implicit.

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