add_issue_labels

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

With no annotations, description provides key behavioral traits: additive operation, parameter type distinction (names not IDs), and error condition. Could mention idempotency or authorization but sufficient for this simple 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?

Three sentences, no wasted words. Front-loads purpose and key constraints.

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 additive mutation without output schema, description covers purpose, parameters, preconditions, and behavior. No gaps.

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 coverage is 100%, so baseline 3. Description adds value by clarifying that labels are 'NAMES (strings) — NOT ids', which helps avoid misuse.

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?

Clearly states the verb 'Add' and resource 'labels to an issue by its index'. Distinguishes from siblings like replace_issue_labels by explicitly noting additive behavior.

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 clear context: use valid names from list_labels, warns of 404 error for invalid names. Implicitly differentiates from replace/remove by stating additive nature, but no explicit alternatives mentioned.

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