unblock_contact

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

Annotations give the safety profile (non-readOnly, non-destructive, idempotent, open-world), and the description adds substantial context beyond them: the primary-device prerequisite and its exact failure mode, that the contact is not notified, that unblocking accepts their message request and re-shares the profile, and that changes sync to linked devices.

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 with the core action and effect, then the prerequisites and side effects. Dense but every sentence carries information; the only mild cost is that the caveats are packed into one long paragraph.

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?

No output schema exists, but the description supplies the return value ('status unblocked and number'), the failure mode, the side effects, and the alternatives. An agent has everything needed to invoke and interpret it.

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?

Only one parameter and schema coverage is 100%, so the schema already documents 'number (E.164 format)'. The description reinforces the E.164 requirement but adds no syntax beyond that, which is appropriate for a single-param tool.

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 (unblock) and resource (contact) plus the immediate effect ('so their messages and calls reach you again'). It is clearly distinguished from its sibling block_contact, which it names directly.

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 routes the agent: use list_contacts with blocked=true to find blocked contacts, block_contact to reverse the action. It also states the no-op case for unblocking a non-blocked contact, leaving nothing to inference.

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