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

Annotations declare destructiveHint=true and idempotentHint=false, so the safety profile is partly covered; the description adds genuinely new behavioral context by disclosing that setting is_primary_champion auto-clears any previous primary (at most one per account). That is exactly the kind of side effect an agent must know before calling. It does not discuss permission requirements or response shape, but those are lower value here.

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 short blocks (core semantics, when-to-use, example) with the most decision-relevant facts front-loaded. Slight redundancy in restating the role default list that also appears in the schema, but no filler sentences.

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 a 5-parameter mutation tool with full schema coverage, an output schema, and annotations, the description supplies everything else an agent needs: when to invoke, id-resolution prereq, exclusivity side effect, and the sibling distinction. Nothing material is missing.

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%, so the baseline is 3; the description adds real meaning beyond the schema by enumerating the seed role values and explaining the exclusivity semantics of is_primary_champion. It stops short of describing notes handling in prose, which the schema already covers.

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 ('Link a contact to an account') and immediately differentiates from the sibling concept opportunity_contacts by explaining that account_contacts persist across the customer relationship. An agent can select it confidently 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?

Explicit 'When to use' section plus a worked example ('Add Sarah Chen as the primary champion at Acme'), and a prerequisite telling the agent to resolve ids via search_* first rather than inventing them. It also names the near-sibling remove_account_contact implicitly through the inverse framing, and contrasts with opportunity_contacts.

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