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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the agent knows this is a mutating operation. The description adds the partial-update behavior ('Only provided fields are updated; omitted fields remain unchanged'), which is valuable and not in the schema. However, it doesn't disclose what happens on failure, whether changes are reversible, or any side effects on dependent entities. No contradiction with annotations.

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?

The description is a single, efficient sentence that front-loads the action and immediately states the most important behavioral nuance (partial update). No wasted words. It could arguably add a hint about required groupId, but the schema already marks it required.

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 destructiveHint=true and no output schema, the description is adequate but thin. It covers the core partial-update semantics, but an agent might benefit from knowing whether the update is atomic, whether it can be undone, or what the response contains. The schema covers parameters well, and the sibling list makes the tool's role clear, so a 3 is fair.

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 100%, so the schema already documents all 8 parameters. The description adds the key semantic that omitted fields are left unchanged, which is critical for update semantics. It does not add per-parameter meaning beyond the schema, but the schema descriptions are already rich (e.g., status 'DISABLED = emergency stop', executionLimit 'Counts groups, not rules'). Baseline 3 is appropriate.

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?

The description states a clear verb and resource: 'Update a policy group.' It distinguishes itself from sibling tools like lexq_groups_create, lexq_groups_delete, and lexq_groups_get by the verb 'update.' However, it doesn't explicitly differentiate from lexq_groups_reorder or lexq_rules_update, though the resource 'policy group' is clear enough.

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 description implies usage: call this when you need to modify an existing policy group. It does not state when to use alternatives like lexq_groups_create or lexq_groups_reorder, nor does it mention any prerequisites (e.g., group must exist). The partial-update semantics ('Only provided fields are updated') is a useful usage hint, but no explicit when/when-not guidance is given.

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