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

The annotations already signal that this is a write operation (readOnlyHint=false) and not destructive. The description adds only that labels organize posts/media, which is more about purpose than behavior. It does not disclose side effects, defaults, or permissions, but no contradiction exists between description and 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 two short sentences with no filler. The first sentence communicates the core action and scope, and the second gives direct usage guidance.

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 creation tool with three schema-covered parameters and no nested objects, the description plus schema provides enough information for an agent to invoke it correctly. The lack of output schema information is a minor gap given the low complexity.

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 parameters name, type, and color are already fully documented in the schema. The description mentions 'posts or media files,' loosely aligning with the type enum, but it does not add meaningful detail beyond the schema. Baseline 3 applies.

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 a clear verb and resource ('Create a new label') and adds the domain context of organizing posts or media files. It does not explicitly distinguish itself from the sibling label tools like list_labels, update_label, or delete_label, but the word 'new' combined with 'Create' makes the creation intent unambiguous.

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 explicitly says 'Use this when the user wants a new label/tag,' giving direct guidance for when this tool is appropriate. It does not mention alternatives (e.g., update_label for existing labels) or exclude cases where it should not be used, so it stops short of full differentiation.

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