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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds genuine behavioral context beyond that: unroutable stops surface in `unassigned` with a reason, over-limit shifts emit `driving_limit_warning`, low bridges come back as `low_bridges`, and the map auto-renders without a road line. It stops short of describing pagination/size limits on the returned link sets.

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?

Long but information-dense and front-loaded: purpose first, then output/warning behavior, then the render caveat. Each sentence carries new signal (link chaining logic, warnings, render semantics), though the middle discussion of Google Maps link chaining is more detailed than an agent strictly needs to select the tool.

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 10-parameter tool with nested `source` and no output schema, the description goes a long way toward explaining what comes back (chained maps links, `unassigned`, warnings) and when render matters. The remaining gap is the `source` ingestion variants and return_to_depot behavior, which are only covered by the schema text.

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 coverage is 70%, so the schema documents most fields (depot, stops, traffic, service_minutes). The description re-states scope that maps onto drivers/shift_hours and elaborates render's return values (link, GeoJSON, KML), but leaves return_to_depot and the source column-detection options unexplained beyond what the schema already says.

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 first sentence names a specific verb and resource with hard scope: 'Split up to 100 stops across up to 10 drivers from one depot and put each driver's stops in the best order on real roads.' It is instantly distinguishable from the other map/route siblings (render_map, update_map, get_road_distances) because it produces a multi-driver ordered plan rather than a single artifact.

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?

Gives explicit conditional use for render ('Set render to true only when the user wants to keep or share the map') and notes update_map can modify a kept map afterwards. It does not name when to prefer get_road_distances, get_travel_time_area, or render_map for simpler needs, so exclusion guidance is incomplete but present.

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