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

Annotations only say this is a non-destructive write; the description adds the critical trait that the tool is PROPOSED and never executed directly, returning status='confirmation_required' with an action_id and plan_token, and that the write requires a follow-up confirm_action. That confirmation-gate behavior is not derivable from the annotations or schema and materially changes how an agent must drive the call.

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?

The purpose and parameter summary are front-loaded, and the labeled CONFIRMATION block makes the non-obvious part skimmable. 'Additive and low-risk' largely restates annotations (destructiveHint=false), which is the one sentence that doesn't earn its place.

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 3-parameter tool with no output schema, the description covers scope, parameter expectations, and the full confirmation lifecycle, which is the information an agent most needs. Remaining gaps are minor, such as uniqueness/name-collision behavior and what a successfully created habit contains after confirmation.

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%, so the description must carry the parameter burden. It does enumerate all three parameters and flags which is required, but 'cadence' just repeats the enum values and 'target_per_period' is left as a bare name with no explanation of the period it is measured against.

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 ("Create a habit to track") plus its scope ("in the caller's active workspace"). It explicitly positions itself against the sibling log_habit, so an agent can choose between creating and logging without opening either 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?

It names the complementary tool and the precondition that log_habit needs an existing habit, which implies create_habit comes first in the workflow. It does not state explicit exclusions (e.g., what to do if a habit with that name already exists), so it falls short of a full when/when-not treatment.

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