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

Annotations already declare non-read-only, non-idempotent, non-destructive and open-world, so the bar is lower; the description still adds real behavioral context beyond them: public visibility ('Shown publicly'), ordering ('newest first'), a hard quota ('At most 20 per goal'), and no cost ('Free on every plan'). It does not mention auth/permission requirements or what happens past the 20-note cap.

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?

Four short sentences, front-loaded with the core action before visibility, quota, and pricing details. Tight overall, though 'Free on every plan' is the weakest sentence for an agent deciding how to call the tool.

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 two-parameter mutation with an output schema already covering return values, the description supplies visibility, ordering, quota, and cost. It leaves auth requirements and the edit/delete counterpart (delete_goal_update) unaddressed, but nothing critical to 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 coverage is 50%: body carries a maxLength and description, while goalId has none. The description's 'short note' loosely corroborates the 280-char limit but adds no format, syntax, or identity semantics for goalId, so it does not compensate for the gap. Baseline 3 is appropriate for this coverage level.

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 a short note under a goal') and scopes the content ('saying what the money did'), which cleanly separates it from create_goal, update_goal, and the reply/support tools. An agent can identify this as the sub-resource-append operation 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?

Usage is implied rather than stated: there is no when-to-use vs. when-not guidance, and the obvious alternative, delete_goal_update, is never mentioned. The 'at most 20 per goal' cap hints at a boundary condition but doesn't tell the agent what to do when exhausted.

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