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

Annotations already declare non-read-only, non-idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely non-obvious behavior beyond that: expectedSpecVersion gates the write to prevent stale-write races. It stops short of saying what happens on a version mismatch or whether the spec version is bumped afterward.

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, and the core action is front-loaded before the concurrency constraint. Every sentence carries distinct 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 a very deep nested layer schema and no output schema, the description leaves real gaps: it never says what the call returns (new spec version? the layer id?), nor that callers must re-read the project to obtain a fresh expectedSpecVersion for subsequent writes. Adequate but not complete for the complexity involved.

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%, so the description must compensate — and it does for the one non-obvious parameter, explaining WHY expectedSpecVersion is required rather than just that it is. projectId is self-evident by format, and title/position carry their own schema descriptions, so the remaining gap is small.

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 origins (dataset, collection, or map in context), so the agent knows exactly what the tool does. It does not distinguish itself from near siblings like project_duplicate_layer or studio_add_layer, which keeps it out of 5 territory.

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?

Usage is implied by the phrase "from a dataset, collection, or map already present in its context" — the caller can infer this is for introducing a new layer rather than modifying an existing one. There is no explicit when-to-use versus project_duplicate_layer, studio_add_layer, or project_create_theme, and no stated preconditions beyond the version field.

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