block_contact

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

Despite no annotations, the description thoroughly covers behavioral traits: local+network propagation, no notification to blocked contact, silent discard of messages, suppression of delivery receipts, no deletion of history, persistence, and reversibility.

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?

Description is relatively long but well-structured with front-loaded purpose and clear separation of behavior and usage. Each sentence provides value, though minor redundancy exists.

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 single parameter well-described in schema, no output schema needed, and comprehensive behavioral disclosure, the description is complete for effective tool invocation.

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 'number' with schema description (E.164 format). Schema coverage is 100%, so description adds no additional meaning beyond schema. Baseline 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?

Description explicitly states 'Block a Signal contact so they can no longer send you messages or call you.' It clearly identifies the verb (block) and resource (contact), and distinguishes from siblings like unblock_contact and remove_contact.

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?

Description provides clear usage context: 'Use when you want to permanently stop receiving messages from a contact.' It explicitly states when not to use ('Do NOT use as a temporary mute' and 'Do NOT use to remove a contact') and provides alternatives (unblock_contact, remove_contact).

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