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

No annotations are provided, so the description carries the full burden. 'Write' implies mutation, but it never states whether saving stops overwrites or appends to an existing day, whether auth is required, or whether the operation is reversible — critical for a calendar-write tool.

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 short sentences, front-loaded with the action and free of filler. The two trailing parameter sentences are redundant against the schema, but they cost little and the whole description is appropriately brief.

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 required-parameter mutation tool with no annotations and no output schema, the description is thin. It omits overwrite/replace semantics, auth requirements, and any indication of what a successful save produces — an agent calling it has unresolved questions.

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 schema already documents both date format and the listing_id-based stops array. The description's two parameter sentences just restate what the schema says, adding no format, ordering, or constraint detail beyond it. Baseline 3 applies.

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 states a specific verb and resource ('Write plan stops onto a calendar day'), which is more than a restatement of the name. However, it offers no differentiation from near-siblings like plan_outing or manage_saved_plans, leaving the agent to guess which save/plan tool applies.

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?

There is no when-to-use guidance at all. With siblings plan_outing and manage_saved_plans in the same family, an agent gets no signal on when this write tool is the correct choice versus those alternatives.

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