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

Annotations already declare destructiveHint=true and openWorldHint=true; the description adds real value on top by disclosing the side effect that routers fetching by that tag will now receive the new artifact, plus the return shape (ID and digest or error). That is meaningful mutation-impact context beyond the annotation flags.

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?

Front-loads the action, then states consequences, then returns, then inputs — every sentence contributes and nothing is padded. The final input sentence is slightly redundant but justified at 0% schema coverage.

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?

Covers the mutation's blast radius (tag reassignment affecting router fetches) and error behavior, which is what an agent most needs before a destructive write. An output schema exists, so the return description is a bonus rather than a 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 0%, so the description carries the burden. It names all three inputs ('the graph ID, the tag name, and the artifact digest') but adds no format or constraint detail for the digest or tag naming, so it identifies the parameters without fully compensating for the empty 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?

Names a specific verb and resource ('Assign a tag to a graph artifact') and anchors it to a known CLI equivalent ('rover graph-artifact tag'). An agent can distinguish it from GetGraphArtifactTags and UntagGraphArtifact without opening any schema.

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?

Gives clear create-or-move semantics ('If the tag does not exist, it is created. If it exists, it moves to this artifact'), which tells the agent exactly what state it may land in. It does not explicitly name UntagGraphArtifact as the inverse or state when not to use this, so it stops short of full alternative routing.

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