add_habit

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

No annotations exist, so the description carries the full burden. It does disclose two useful behavioral facts beyond a bare 'create': the return value is the new id, and target_count is constrained to 1..99 with a default of 1 (a validation rule that would otherwise surface as a runtime error). It says nothing about duplicate handling, the meaning of the client-supplied id field, or whether created habits appear immediately in list_habits.

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 short sentences, front-loaded with the action and return value, then the one non-obvious parameter constraint. No filler, although the parenthetical is dense enough that clarity could be trimmed.

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 6-parameter mutation tool with no annotations, no output schema, and zero schema coverage, the description covers purpose, return value, and a single parameter. The semantics of the optional id, icon, unit, and color fields — and expected input formats — are absent, leaving the agent to guess on most of the surface.

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 0% across 6 parameters, so the description must compensate and it largely does not. Only target_count is explained (range 1..99, default 1) — genuinely useful since the schema shows only a nullable integer — while id, icon, unit, color, and title remain undocumented in both places.

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?

Uses a specific verb+resource ('新建一个习惯' / create a habit) and adds that it returns the new habit's id. The noun 'habit' naturally separates it from add_todo/add_countdown siblings, though no sibling is named explicitly.

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?

The 'create' verb implicitly routes the agent away from update_habit, check_habit, or delete_habit, but there is no explicit statement of when to use this instead of those alternatives, nor any preconditions (e.g. duplicate titles).

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