block_contact

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

With no annotations, the description fully discloses behavioral context: the block is local and propagated, the contact receives no notification, messages are silently discarded, delivery receipts suppressed, history not deleted, and block persists across restarts and is reversible.

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?

The description is front-loaded with the core purpose and efficiently covers key behavioral points. It is slightly lengthy but justified by the need to explain nuanced behavior (silent discard, persistence). Every sentence adds value.

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?

Given the tool has one parameter, no output schema, and no annotations, the description covers all necessary behavioral aspects: notification status, message handling, history preservation, persistence, and reversibility. No gaps remain.

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?

The single parameter 'number' has 100% schema coverage with a clear E.164 format description. The description adds no additional parameter detail beyond what the schema already provides, so a baseline score of 3 is appropriate.

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 description explicitly states the action ('block a Signal contact'), the resource ('contact'), and the effect ('prevent messages/calls'), clearly distinguishing from sibling tools like remove_contact (which removes the contact altogether) and unblock_contact (which reverses the block).

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 provides explicit when-to-use ('permanently stop receiving messages'), when-not-to-use ('temporary mute' or 'remove contact'), and references the alternative unblock_contact for reversal.

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