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

Annotations already declare readOnlyHint=false and destructiveHint=false, and the description adds genuinely new behavioral context: the same-site precondition, that budget amounts and approvals are untouched, and that approval requirements are org-configurable while business workflow approvals always apply. That last note is real operational context an agent needs before calling a mutating link operation.

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, front-loaded with the action and its key constraint, followed by the scope and approval caveats. No filler; the approval sentence is slightly long but earns its place as operational guidance.

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 no explanation, and the annotations cover the safety profile. For a two-parameter link operation, the description supplies the site-matching rule and approval caveats that the structured fields do not, leaving only per-parameter naming as a residual gap.

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 0%, so the description must carry semantics — and it does contribute one important constraint: both IDs must reference the same site. However, it never mentions taskId, the nested data.lineItemId shape, or that UUIDs are expected, so the parameter documentation gap is only partially offset.

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 both resources ('site task', 'budget line item'), plus the constraint that they must come from the same site. This clearly separates it from the unlink/delete siblings, though it does not name unlink_task_budget_line_item or list_task_budget_links explicitly.

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 carves out scope ('Does not change budget amounts or approve the budget'), which implies this is a pure association operation, but it never states when to use it versus alternatives such as update_budget_line_item, bulk_assign_budget_line_items, or unlink_task_budget_line_item. Usage is inferable but not spelled out.

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