add_issue_labels

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

With no annotations, the description carries the full burden. It discloses additive behavior, deduplication, and error condition. However, it does not mention response format or permissions. Still, it covers key behavioral aspects well.

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?

Three sentences, front-loaded with the action, no filler. Every sentence provides essential information. Extremely concise and well-structured.

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 an additive label operation with 4 parameters and no output schema, the description covers the core behavior, error conditions, and references list_labels for validation. It is complete enough for an agent to use correctly without ambiguity.

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?

Input schema covers 100% of parameters. The description adds value by clarifying that labels are names (not IDs) and that repo/owner have defaults, which the schema only hints at via descriptions. This helps agents use the parameters correctly.

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 clearly states it adds labels to an issue by its index, specifying that labels are names, not IDs. This distinguishes it from sibling tools like remove_issue_label, replace_issue_labels, and clear_issue_labels, which have different purposes.

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 explicit guidance: get valid names from list_labels, warns about 404 errors for non-existent names, states additive behavior and duplicate filtering. Implicitly tells when not to use it (e.g., for replacement, use replace_issue_labels).

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