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

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: expectedSpecVersion exists for optimistic concurrency control against stale writes. It does not say what happens on a version conflict, whether the write bumps the spec version, or whether setting the same visibility twice is a no-op, so it is additive but incomplete.

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, no filler, and the core action is front-loaded before the concurrency caveat. Nothing is redundant with the 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?

This is a non-idempotent mutation with a nested input object, no output schema, and no annotation detail about failure modes. The agent is left guessing how to source expectedSpecVersion, what a version mismatch returns, and whether the response includes the new spec version needed for subsequent calls. The description covers the action but not enough of the calling contract.

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 description coverage is reported at 0%, so the description needs to carry the load. It only explains the purpose of expectedSpecVersion; projectId and the nested input object (layerId, visibility) get no explanation of format, source, or interaction. The inline enum on visibility partially compensates, but overall coverage is thin for a nested three-parameter tool.

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: 'Show or hide one layer in the project map.' That clearly separates it from sibling layer tools like project_set_layer_filter, project_set_layer_zoom_range, and project_update_layer_style. It stops short of explicitly naming those siblings, so a 4 rather than a 5.

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?

There is no guidance on when to reach for this tool versus the many adjacent layer-configuration siblings, and no stated prerequisites such as required permissions or how the caller should have obtained a valid spec version. The only contextual hint ('required to prevent stale writes') explains a parameter, not when to use the tool.

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