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

Annotations already declare readOnly=false, destructive=true, idempotent=true, and openWorld=true, so the safety profile is covered. The description adds a genuinely non-obvious trait: this is a partial update where omitted fields are left untouched, despite the underlying POST verb. It does not say what a bad group_id does or what the response contains.

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?

A single dense sentence with the mutation warning front-loaded as "WRITE:" and the endpoint appended. No filler, nothing restated.

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 an 8-parameter partial-update tool with full schema documentation and no output schema, the definition covers what the agent needs to invoke it correctly. Minor gap: no mention of authorization requirements or failure behavior for an invalid group_id.

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 coverage is 100% and every field is documented with constraints, so the baseline is 3. The sentence "only the fields you pass are changed" adds real semantic value about the seven optional parameters — it tells the agent that omitting a field means "leave as-is," which the schema cannot express.

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?

"change fields of an existing resource group" gives a specific verb and resource, and the "existing" qualifier separates it from scheduleit_create_group. It does not name any sibling or alternative explicitly, so it stops short of full sibling differentiation.

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 only implied: the agent can infer "use this to modify a group that already exists, use create_group otherwise." There is no explicit when-to-use versus update_event/update_resource guidance, no prerequisites, and no exclusions.

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