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

Goes well past the annotations (readOnlyHint=false, idempotentHint=false, destructiveHint=false) by disclosing the storage side effect (value becomes success_metric.current), the recomputation behavior, the returned evaluation fields, baseline overwrite semantics, and two distinct 422 failure modes. This is exactly the extra behavioral context annotations cannot carry.

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-loaded with the core action, then effects, then sibling routing, then args. The embedded example JSON and the baseline fallback sentence are slightly heavy, but each earns its place by removing a real ambiguity; nothing is padding.

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?

With no output schema, no annotation detail beyond hints, and 0% schema coverage, the description nonetheless covers the return payload, the failure modes, and the preconditions. An agent has everything it needs to call this correctly and interpret the result.

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 0% and the schema carries only bare types, so the description must compensate — and it does: goal_id is a UUID, value may legitimately be zero, and baseline's overwrite behavior plus its fallback chain (omitted and none stored → previous measurement → this one) is spelled out. No ambiguity remains for any of the three parameters.

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 precise verb+resource pair — record a measured value for a goal's success metric and re-evaluate the goal — and immediately distinguishes itself from the similarly named update_goal and close_goal. An agent can route between these three siblings 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?

Explicit when-not guidance: 'It does not close the goal; use close_goal when success_met is true and you want to conclude it.' It also gives the prerequisites (a success_metric with target/operator, configured via update_goal) and the exact conditions that make the call fail.

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