label

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

No annotations are provided, so the description carries the full burden of disclosing behavior. It states that labels are added, but does not explain whether existing labels are preserved or replaced, whether duplicate labels are handled, or what side effects occur. This is a meaningful gap for a mutation tool.

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?

A single front-loaded sentence states the action first and then adds the input format parenthetically. There is no filler, and every part of the description 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?

The description is close to the minimum viable definition for a simple labeling tool, and the presence of an output schema reduces the need to explain return values. However, it still omits important context about account and the append-versus-replace semantics of adding labels.

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 compensate. It explains the format of the labels parameter (comma-separated names or ids), but leaves account and thread_id to be inferred from their parameter names. account in particular is ambiguous.

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 uses a specific verb and resource ('Add labels to a thread') and clearly differentiates this from the sibling unlabel tool. The parenthetical also clarifies that labels can be supplied as names or ids, leaving no doubt about what the operation does.

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 clearly communicates the use case: when labels need to be added to a thread. It does not explicitly mention alternatives or exclusions, but the additive framing is unambiguous enough for an agent to know when to invoke this tool.

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