list_labels

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

It explicitly states the tool is read-only and 'does not mutate GitLab data,' matching the readOnlyHint annotation while adding value. It also discloses how errors are surfaced for missing resources, invalid identifiers, insufficient permission, and rate limits, which is useful beyond the annotations.

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 description is reasonably concise and front-loaded with the core purpose. The final sentence contains some generic boilerplate about 'project_id or group_id' and 'exactly as documented' that slightly dilutes the tool-specific value, but it is not bloated.

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 straightforward list operation with a fully documented schema, the description covers purpose, usage context, read-only behavior, error behavior, and identifier handling. There is no output schema, but the return type is reasonably inferable from the tool name and siblings; omitting an explicit response shape is a minor gap.

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 schema already documents all six parameters. The description adds only generic guidance about using numeric IDs or URL-encoded paths and following documented pagination fields, which is helpful but not detailed enough to raise the score above the baseline.

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 the tool's verb and scope: 'List labels for a project.' It also distinguishes itself from the corresponding single-resource get tool by explaining the collection-vs-single-resource distinction, which differentiates it from siblings like get_label.

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?

The description explicitly says to use this tool 'for a collection of resources' and to choose the corresponding get tool when a single resource is already known. This gives an agent clear, actionable routing guidance relative to sibling tools.

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