contacts_write

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

Annotations already declare destructiveHint=true and non-idempotent, but the description adds the important qualifier that merge and delete 'cannot be undone automatically' and instructs confirmation, plus it clarifies merge semantics (the source contact disappears, the target is kept). It doesn't explain what happens to data on unmerge or what the response contains, keeping it short of a 5.

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?

Front-loaded summary plus the destructiveness warning before the action list, then a compact pipe-delimited breakdown. Every clause carries either a verb, a risk, or a required parameter; nothing is redundant.

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 9-parameter destructive tool with no output schema, this covers the essential calling information: which action does what, what each action requires, and which are irreversible. It stops short of describing the result of unmerge (whether a new contact is created) or response shape, which would fully close the loop.

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?

With only 56% schema coverage and no conditional required fields in the schema, the description carries the critical mapping of action to required IDs (sourceIdentityId/targetIdentityId, identityId/convoIds, consentStatus), which is genuinely additive. It leaves mode, agentId, and consentSource to the schema, so it is not fully complete.

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 opening sentence names four specific verbs (merge, split, update consent, delete) operating on a single resource (contact), and the per-action breakdown makes each operation unambiguous. An agent can distinguish this from contacts_read and from sibling write tools 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?

Each action is annotated with the parameters it needs, which is effectively conditional guidance, and the description explicitly says to confirm with the user for merge and delete. What is missing is routing guidance relative to alternatives, e.g. when to look up a contact via contacts_read before merging.

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