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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), and the description adds real behavioral detail beyond them: the case-insensitive uniqueness constraint and the fact that a duplicate in any casing returns an error, which explains why the operation is not idempotent. It does not state permissions or what the call returns.

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 tight sentences with the core verb front-loaded and constraints packed into a single parenthetical. Slightly redundant with the schema descriptions, which keeps it off a 5.

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 3-param creation tool with full schema coverage and annotations carrying the safety profile, the description covers the essentials. It omits what the call returns (the created tag or its id) and any precondition that the project must already exist, which is a minor gap given no output schema.

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 baseline is 3 — the description's parenthetical about the name being unique per project and the color coming from a preset palette largely restates what the schema already documents for those two properties. No added syntax, format, or edge-case semantics.

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?

StartsWith a specific verb+resource: "Create a new tag for a project." The verb alone separates it from update-tag-tool, delete-tag-tool, and get-tag-tool siblings, and the scoping to a project is stated explicitly.

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?

No guidance on when to choose this over alternatives — nothing about checking whether a tag already exists via list-tags-tool, or falling back to update-tag-tool rather than re-creating. The duplicate-error note is a constraint, not routing guidance.

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