buffer

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

With no annotations at all, the description carries the full burden and does a reasonable job: it discloses the geodesic metre-based semantics, the default dissolve behavior (merging into one polygon), the extra area_km2 output in that case, and that results come back as GeoJSON plus a result_id. It omits permission/auth needs, cost of large buffers, and how the server-side cap interacts with the default limit of 100.

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 core action and units, then the input modes, then the dissolve/output behavior. Dense parenthetical shorthand ('+filters', 'also returns its area_km2') without filler; every clause conveys operational information.

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 7-parameter, 1-required tool with no annotations and no output schema, the description covers the essentials: units, input modes, dissolve semantics, and return shape. Gaps remain around lon/lat and layer being effectively mutually exclusive, what result_id is for downstream use, and the practical effect of limit/pagination.

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 86%, so the baseline is 3, and the description earns above that by explaining the one parameter the schema leaves bare: dissolve merges features into a single polygon and additionally returns its area_km2. It also reinforces the metre-unit semantics of distance and the point-vs-layer relationship between lon/lat and layer.

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 ('Buffer geometries by a distance in METRES (geodesic)') and enumerates the two input modes (lon/lat point vs. layer features with filters). It does not explicitly contrast itself with siblings like within_distance or spatial_filter, so an agent must infer that this creates geometry rather than selecting features, but the transformation nature of the tool is unmistakable.

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 phrase 'Buffer a point (lon/lat) or the features of a layer (+filters)' gives mode-selection guidance, which is genuinely useful for choosing between the two call shapes. However, there is no statement of when to prefer this over within_distance (search by proximity) or spatial_filter (select by geometry), so the routing decision against siblings is left to inference.

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