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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful non-schema context: the required auth scope and the cost-accounting semantics of a link. It stops short of disclosing duplicate-link behavior, which matters given idempotentHint=false.

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?

Three sentences, no filler; purpose is front-loaded, then prerequisites and parameters, then the critical cost caveat. Every sentence carries distinct information.

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?

With no output schema, the description still covers what the tool does, the required scope, and the argument shape, which is complete enough to invoke it correctly. The only notable gap is return/duplicate behavior, which is minor in this context.

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 each ID parameter points to its resolver list tool, so the baseline would be 3. The description goes beyond the schema by stating the mutual-exclusion rule ('exactly one of work_order_id, pm_schedule_id, project_id') that the JSON schema does not encode. It adds no format or edge-case detail beyond that.

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 (Link) and resource (purchase order) plus the three linkable targets (work order, PM schedule, project), and distinguishes itself from the cost-charging behavior of setting project_id/work_order_id on the purchase order itself. An agent can tell this apart from create_purchase_order_line or create_purchase_order_link's siblings without opening the schema.

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?

Explicitly names the required scope (purchase_orders:write), the required parameter plus the exactly-one-of constraint, and gives a when-not condition: a link does not add to committed cost, so to charge cost you instead set project_id/work_order_id on the purchase order. This is precise routing guidance rather than implied usage.

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