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

With annotations already covering write/non-idempotent/non-destructive, the description still adds material behavioral context: the plan must be in an undistributed state, recipient contact data is persisted on the stop, and Spoke may contact the recipient later even though 'nothing is sent now'. The deferred-side-effect timing is exactly the kind of thing annotations cannot express.

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?

Front-loaded with 'WRITE:' and the precondition, then usage guidance, then the raw endpoint last. Three tight sentences, every one carrying information an agent needs.

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 mutation tool with no output schema and annotation coverage of the safety profile, the description covers prerequisites, side effects, and the bulk alternative. The one gap is that it never says what comes back (e.g. whether a stop id is returned for later use), which matters for a create-then-reference workflow.

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?

Top-level schema coverage is 0% (only the nested 'stop' object carries per-field descriptions), so the description does compensate by explaining the address requirement and the text-vs-lat/lng alternative. However it says nothing about plan_id semantics or the optional nested fields it doesn't repeat, so it only partially fills the gap.

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 ('add one stop') plus resource ('to a writable plan') and the critical precondition that the plan is not yet distributed. It is immediately distinguishable from spoke_import_stops (bulk) and from the getter siblings, so no schema opening is needed to disambiguate.

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?

Explicitly names the alternative and the condition that selects it: 'For many stops use spoke_import_stops.' It also states the when-not condition inline ('writable (not yet distributed) plan'), leaving nothing to inference.

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