update_label

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

Annotations indicate readOnlyHint=false, idempotentHint=true, destructiveHint=false. The description adds the explicit note 'This tool cannot delete labels,' which clarifies the non-destructive scope. However, it doesn't disclose behavior on non-existent labels (does it fail or create?) or whether partial updates are allowed (only some fields passed). With idempotentHint already given, the description adds modest value.

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?

Two sentences, zero filler. Front-loads the action ('Update an existing label name, color, or description') and adds one useful exclusion. Every word earns its place.

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 7-param tool with 3 required params, low schema coverage, no output schema, and annotations present, the description covers the what (fields updatable) and the boundary (cannot delete). It could add more on what happens if currentName doesn't match any existing label, or note that it's a repo-scoped operation. Given the description's brevity and the idempotentHint, it's adequate but not fully complete.

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 very low at 14% - only 'repository' has a description. The description steps in by identifying the three mutable fields (name, color, description) and implying currentName is the identifier to locate the label. This meaningfully compensates for the schema gap, though it doesn't explain hostname or account semantics beyond their presence in the schema.

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 states 'Update an existing label name, color, or description' - a clear verb+resource with the specific mutable fields listed. It distinguishes from sibling create_label and delete operations (list_labels, create_label exist as siblings). It doesn't explicitly compare to siblings but the purpose is clear.

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?

It clearly states what it cannot do ('This tool cannot delete labels'), which is a useful exclusion given delete_repository and delete_pull_request_review_comment siblings exist. However, it provides no guidance on when to use this versus create_label (new labels) or list_labels (retrieval), nor any prerequisites about requiring the label to exist first.

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