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

Annotations declare a non-readOnly, non-idempotent, non-destructive mutation. The description adds genuinely useful context beyond that: expectedSpecVersion exists to prevent stale writes, telling the agent this is an optimistic-concurrency write. However, it does not say whether configuring a legend replaces or merges existing legend entries, or what happens when legend is null.

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 short sentences, front-loaded with the action and followed by the one non-obvious constraint. No filler and nothing needs to be reordered.

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 deeply nested legend payload and no output schema, yet the description omits replace-vs-merge semantics for entries, per-type requirements (item type must match layer geometry), and whether a null legend disables the legend entirely. Those are the details most likely to cause a wrong call.

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%, and the description explains only one of three required parameters: the purpose of expectedSpecVersion (stale-write prevention), which the schema alone does not convey. It says nothing about the shape of `input`, layerId, or projectId beyond what the nested schema documents.

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: configuring a project map's legend and its entries. It is clearly distinct from the styling/popup siblings, though it never explicitly contrasts itself with project_update_layer_style or project_configure_popup, so the differentiation is implicit.

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?

No guidance on when to use this versus sibling tools such as project_update_layer_style or project_configure_popup, and no exclusions or prerequisites. The only usage-adjacent statement is the concurrency note, which is a requirement rather than routing guidance.

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