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

Annotations already indicate this is a mutating operation (readOnlyHint=false) and not destructive (destructiveHint=false). The description adds the tracking type definitions, but not behavioral details like return values, side effects, or permission requirements. It neither contradicts annotations nor adds substantial behavioral context beyond the creation action.

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 description is two sentences with no filler. It front-loads the core purpose and then concisely summarizes the main disambiguating information about tracking types. Every element earns 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 9-parameter creation tool with no output schema, the description plus the fully covered input schema is sufficient. The tracking type summary adds critical context for choosing the right fields. It could be more complete by noting that name is required and that certain fields apply only to specific tracking types, but the schema already documents those details clearly.

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 100%, so the baseline is 3. The description adds meaningful semantics to the tracking_type enum by explaining what each value means (check = daily toggle, count = hit a number, duration = minutes, times_per_week = weekly frequency), which the schema does not fully convey. This helps an agent correctly pair tracking_type with target_value, target_duration, and times_per_week.

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 clearly states the verb and resource: 'Create a new habit.' It also distinguishes the tool from siblings like log_habit and update_habit by emphasizing creation and listing tracking types. No ambiguity remains about the tool's core purpose.

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 description implies that this tool is for creating habits, but it does not explicitly say when to use it instead of related tools like log_habit, update_habit, or list_habits. Sibling names make the distinction inferable, but no explicit alternatives or exclusions are provided.

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