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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, and openWorldHint=false. The description adds useful context beyond these hints: it explains what idempotency means here ('succeeds without change') and imposes a cross-entity constraint that both prompt and tag must share a project, which is not fully conveyed by the annotations alone.

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, front-loaded with the core action. Each sentence adds a distinct piece of information (purpose, idempotency behavior, project constraint) without redundancy or 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 simple two-parameter attach operation with no output schema and annotations covering the safety profile, the description covers purpose, idempotency, and the key same-project prerequisite. It could optionally mention failure behavior when project ownership does not match, but nothing essential for correct invocation is missing.

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 both parameters are already documented in the input schema. The description reinforces the cross-parameter requirement that prompt and tag share a project, but this duplicates what the tag_id schema description already states, so the baseline of 3 is appropriate.

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?

States a specific verb and resource: 'Attach a tag to a prompt.' The operation is unambiguous and clearly distinguishable from the sibling 'detach-tag-from-prompt-tool' by its verb, and from tag-management siblings like 'create-tag-tool'.

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?

Provides a prerequisite ('Both the prompt and the tag must belong to the same project') and notes idempotent behavior, which implies it is safe to call even if already attached. However, it does not explicitly name or compare against alternatives such as detach-tag-from-prompt-tool or explain when to prefer other tag operations.

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