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

Annotations only declare this as a non-read-only, non-destructive mutation. The description adds real value beyond that: it discloses the side effect that labels are auto-created on the repo if missing, states the required 'repo' scope, and gives the return shape {labels}. It does not address idempotency (re-adding an existing label) or error behavior for a nonexistent issue number.

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 short sentences, each carrying distinct information: the action, the auto-create side effect, and the auth/return contract. The core action is front-loaded and there is no filler.

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 four-parameter mutation with annotations and no output schema, the description covers the essential contract – what it does, the side effect, the scope requirement, and the return value. The remaining gaps are parameter-level detail for owner/repo and label-replacement semantics.

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 only 25% – just the 'labels' array is documented. The description partly compensates by implying 'number' is the issue number and that 'repo' scopes the operation, but 'owner' and the exact owner/repo relationship remain unexplained in both places. That partial compensation supports a middling score.

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 opens with a specific verb and resource ("Attach one or more labels to an issue"), which is unambiguous and clearly distinct from merjax_unlabel_issue by the verb alone. It stops short of explicitly naming the sibling tool for removal, so it lands just below the top mark.

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?

Usage is implied by the operation itself: use this when an issue needs labels. There is no explicit guidance on when not to use it, whether labels are additive or replacing, or how it relates to merjax_create_issue with labels or merjax_unlabel_issue. Adequate but leaves routing to inference.

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