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

Annotations only declare readOnly=false, destructive=false and non-idempotent. The description adds two pieces of context the annotations do not carry: the optimistic-concurrency contract (expectedSpecVersion is required to prevent stale writes) and the source-constraint that the referenced dataset/collection/map must already be in context. It still omits what happens on version mismatch or that repeated calls create duplicate layers.

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?

Two sentences, zero filler, with the main action stated first and the hard prerequisite immediately after. Nothing restates the tool name or title.

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 non-idempotent write with no output schema and 0% top-level parameter coverage, the description is thin. It never says what the call returns, nor the critical follow-on fact that adding a layer changes the spec version agents must pass on their next write, which is the natural consequence of the concurrency contract it introduces.

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 description coverage is 0%, so projectId and position are explained nowhere. The description partially compensates by explaining the semantics of expectedSpecVersion and the origin of the layer payload, and the nested layer schema is itself heavily documented. Position, the insert index, is left entirely unexplained by both description and schema.

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 ("Add a map layer to a project") plus the accepted source kinds (dataset, collection, or map in context). It is clearly distinguishable from the many geobble_project_configure_* and geobble_project_remove_layers siblings, though it never names the closest alternative (geobble_studio_add_layer) to sharpen the boundary.

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 "from a dataset, collection, or map already present in its context" implies the precondition that the source must already exist in the project's context, and the expectedSpecVersion note implies a read-then-write flow. However, it never states when to prefer this over geobble_studio_add_layer or geobble_project_duplicate_layer, and no explicit exclusions are given.

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