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

Annotations already indicate this is a non-read, non-destructive mutation, so the bar is lower. The description adds meaningful behavioral context beyond the annotations: is_admin has consequences for deletion and recycle bin access, and weekly_capacity_percentage affects all resource and utilization calculations. It also clarifies partial-update semantics. 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?

Two sentences with no fluff. The action and partial-update rule come first, followed by targeted warnings about the two high-impact fields. Every sentence earns its place.

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?

Given the 11-parameter, no-output-schema update context, the description covers the partial-update contract and the two behaviorally significant fields. Remaining gaps, such as return value or permission requirements, are minor and not essential for a competent agent to invoke the tool correctly.

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 only 18%, so the description must compensate. It does so for the two least obvious parameters: is_admin and weekly_capacity_percentage. The remaining parameters are mostly self-explanatory by name or already documented in the schema, such as role and employment_type. Critical hidden semantics are covered.

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 clearly states a specific action and resource: 'Update an employee record.' It also adds the partial-update rule, which narrows the tool's behavior. It does not explicitly contrast with hr_create_employee or hr_get_employees, but the resource and action are unambiguous among siblings.

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 when to use the tool: to change an existing employee record. The partial-update statement ('Only the fields you pass are changed') is useful guidance. However, it does not name alternatives or state conditions where another tool should be preferred, leaving sibling differentiation to inference.

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