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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes beyond them by disclosing what comes back: subgoals with ids and done status, after/leads_to arrows, and a locked flag, plus the fact that omitting horizon returns all three periods. It stops short of noting ordering, pagination, or whether empty horizons are included.

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?

Three tight sentences, no filler, with the scope stated first and the usage cue last. Density is high enough that the list of returned fields ('subgoals (ids, done), arrows (after, leads_to) and locked') reads a bit telegraphic, but 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?

There is no output schema, so the description must carry return-value information, and it does: subgoals, arrows, locked flags, and per-horizon grouping. What remains thin is the goal object's own fields and how nested subgoals/arrows are keyed, but the essential shape is present.

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% (date documented as YYYY-MM-DD, horizon only as an enum). The description compensates by explaining that date selects the periods containing another day, which is meaning the pattern alone does not convey, and clarifies that a single horizon can be requested or all three returned.

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?

The description names the resource precisely (goals for month/quarter/year, including subgoals, arrows and locked flags), so an agent knows this is a retrieval of goal state. It is a noun phrase rather than a verb+resource statement and never explicitly contrasts with update_goal/add_goal, but the read nature is unambiguous from the content listed.

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?

'Fits when the user asks about their goals or progress toward them' gives a concrete triggering condition. No exclusions or named alternatives are provided (e.g., when to prefer a broader briefing tool), so it is clear context without routing guidance.

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