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

Annotations declare destructiveHint=true, and the description explains exactly what makes it destructive: the lead receives the campaign label and label triggers may suppress, stop a campaign, pause a campaign, or move a lead to a list. That is substantial behavioral context beyond the annotation flags.

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 front-loaded with the core action, then adds the important trigger effects and the null-clearing rule in two compact sentences. Every sentence adds useful information without repetition.

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 two-parameter destructive mutation with no output schema, the description gives enough context to understand the side effects and clearing behavior. It is nearly complete, though it could explicitly define the id parameter and explain how valid label IDs are obtained.

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 0%, so the description must clarify parameter meaning. It usefully explains that labelId=null clears the label, but it does not explicitly document the id parameter or describe valid labelId values, leaving a meaningful gap.

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 precise verb and resource: set or clear a thread's label. It also names the concrete effects on the lead and campaign, making the tool's purpose immediately distinguishable from thread-reading siblings like get_thread and list_threads.

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 description makes clear when to use the tool: to set a label or to clear it by passing null. It does not name alternatives or exclusions, but the operation is specific enough that an agent can determine appropriate use without opening another schema.

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