Contract Testing: Add Label to Pacticipant

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

Annotations already indicate this is a mutation (readOnlyHint=false), but the description adds no behavioral context beyond the basic action. It does not disclose whether applying an existing label is idempotent, whether duplicate labels can occur, or what side effects or errors should be expected.

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 definition is compact and front-loaded with the core action. The parameter list is somewhat redundant because it duplicates the schema, but it does not significantly bloat the description and the overall structure is clear.

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 mutation, the description plus schema is generally sufficient to invoke the tool. However, key operational context is missing, such as whether adding the same label twice has any effect, whether the label must already exist, and any constraints around the pacticipant name.

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 100%, so the input schema already documents both parameters. The description repeats the schema's parameter names and descriptions without adding extra semantics such as value formats, label existence requirements, or relationships between the parameters.

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 ('Apply') and a clear resource ('label to a pacticipant'), making the operation unambiguous. It also distinguishes naturally from the sibling tool contract-testing_remove_label_from_pacticipant, so an agent can tell addition from removal without opening the schema.

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?

No guidance is provided on when to use this tool versus alternatives, nor are prerequisites mentioned such as whether the pacticipant or label must already exist. The 'Toolset: Labels' label provides minimal grouping context but no explicit decision guidance.

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