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

Annotations already declare the write/safety profile (readOnlyHint=false, idempotentHint=false), and the description adds substantial context beyond them: the 5/25 rubric ceiling per build, the 409 error on overflow, and the live-build default. It does not describe the success response or permission requirements, but discloses meaningful limits and failure modes.

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 dense sentences, front-loaded with the action, then the capacity/error constraint, then the targeting default. Every clause carries information and nothing is wasted.

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 mutation tool with no output schema, the description covers the key behavioral constraints an agent needs (limits, 409, default target). It omits the success return shape and any auth prerequisites, but the annotations and full schema coverage fill most remaining gaps.

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 all five parameters are documented in the schema itself, including build_id's live-build default and the intricate selected_automation_revision_id semantics. The description only restates the build_id default, adding little beyond 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?

States a specific verb and resource ('Add one Agent-specific evaluation rubric to a build') with the qualifier 'Agent-specific' that distinguishes it from sibling rubric tools like createCaseQueueEvalRubric. An agent can tell what this creates and where it lands.

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 context: defaults to the Agent's live build, pass build_id to target a specific revision. It explains the capacity ceiling and the resulting 409 failure. It does not name alternative tools (updateEvalRubric, replaceEvalRubrics), but usage context is clear.

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