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

Annotations already declare readOnlyHint=false, destructiveHint=true and openWorldHint=true, so the agent knows this mutates live data. The description adds only the mild implication that this is a partial field-level update on an existing record; it says nothing about whether omitted fields are preserved, whether changes are reversible, or what permissions are required. With annotations carrying the safety profile, this adds limited extra context.

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 the resource, with the sys_id prerequisite following immediately. No filler or repetition.

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?

An output schema exists, so return values need not be explained, and the annotations cover the destructive/open-world profile. What remains thin is mutation semantics — partial vs. full update, and whether close_notes is mandatory for the resolved/closed states (that rule lives only in the schema). Adequate but not fully complete for a destructive write tool.

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% and each parameter already documents its allowed values (state codes, urgency, priority, close_notes requirement). The description's mention of 'state, priority, assignment' merely restates a subset of the schema and adds no format or constraint detail beyond it, so the baseline 3 applies.

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 ('Update fields on an existing ServiceNow incident') and enumerates the field groups it touches, so the agent knows exactly what operation this is. It does not explicitly differentiate itself from siblings like servicenow_create_incident or servicenow_add_comment, though 'existing' implies update-not-create.

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?

Gives a concrete prerequisite and dependency: the sys_id must come from servicenow_get_incident, which routes the agent through the correct discovery flow. It lacks any when-not guidance (e.g., use servicenow_add_comment for comments, or create_incident for new records), so it falls short of a 5.

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