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

Annotations already flag destructiveHint=true and non-idempotent; the description earns credit for adding real behavioral context beyond that, such as the data inconsistency risk when changing type and the fact that deletion preserves historical data but stops tracking.

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?

Dense and front-loaded, leading with the tool's core purpose before the per-action breakdown. Information-heavy but every clause adds constraint; only slight loss from the run-on structure.

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 destructive nested-object mutation tool with no output schema, the description covers the important operational details (per-action requirements, data risk). The unexplained mode parameter is the only meaningful 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 coverage is only 40%, so the description must compensate, and it does: it explains the metric object contents, what update requires (metricId + partial metric), and enum options. Only the mode parameter and agentId scoping are left to 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 set (create/edit/delete) and resource (custom analytics metric on an agent), and enumerates what each action does. An agent can distinguish this from the sibling custom_metrics_read without opening the 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?

Clear per-action guidance: create needs key+type+description and options for enum, update takes only changed fields, delete keeps historical data. It gives a caution about changing type but never names custom_metrics_read as the read alternative or states prerequisites.

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