get_contact

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds a genuinely useful behavioral rule beyond the structured data — the tie-break that the saved variant wins when duplicate raw contacts share a phone — which an agent could not infer from schema or annotations.

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?

Purpose is front-loaded, the tie-break caveat follows, and the examples come last. Three examples is slightly redundant (the bare-phone case largely repeats the leading-+ case), but nothing is wasted and the structure is easy to scan.

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 zero-required-param read tool with annotations covering safety, the description is largely adequate. With no output schema, however, it never describes what the returned contact contains or what happens when no match is found, which leaves a real gap for a lookup tool.

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 coverage is 100%, so the baseline is 3. The description goes slightly beyond the schema by explicitly confirming that either parameter alone suffices, and the dedupe tie-break clarifies how phone matching resolves when duplicates exist, plus concrete call examples.

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 ('look up a single WhatsApp contact') and names both accepted identifiers (JID or phone number). The word 'single' implicitly separates it from the sibling list_contacts, but no sibling is named outright.

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?

Usage is implied by the nature of a lookup tool, and the description does clarify that either identifier parameter is valid ('both work'). However, it never states when to reach for this instead of list_contacts or export_contacts, nor any exclusions or prerequisites.

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