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

Annotations already cover the read-only, idempotent, non-destructive profile, and the description adds real behavioral context beyond them: the search scope (1-to-1 chats ranked by most recent exchange plus contacts), the four possible outcomes, and per-outcome handling policy (ambiguous → ask, incomplete → do not auto-send, resolved → send immediately without extra confirmation).

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?

Dense but front-loaded: the core purpose lands in the first clause, followed by search behavior, outcomes, and examples. The outcome list is information-packed and each clause earns its place, though the single long paragraph could be structured for faster scanning.

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, so the description carries the return-value burden and does so fully by enumerating resolved/incomplete/ambiguous/not_found with the action for each. Combined with 100% schema coverage and clear annotations, nothing an agent needs to call this correctly is missing.

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 adds negative guidance ('never pass a name as chat_id or user_id') and clarifies the name field's accepted forms, which the schema also covers. It goes slightly beyond the schema without documenting provider/account_id edge behavior.

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+resource (resolve a name/nickname/phone/handle into an exact messaging recipient) and scopes it precisely to WhatsApp/Instagram/Telegram 1-to-1 chats and contacts. An agent can immediately distinguish it from siblings like messaging_find_chat_by_user or message_resolve_chat, which operate on chats rather than people.

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 says to use this BEFORE sending, gives concrete trigger phrases ('send a WhatsApp to Julien', 'reply to Marie on Instagram'), and routes LinkedIn cases to linkedin_resolve_person + linkedin_start_conversation. It also states a hard exclusion: never pass a name as chat_id or user_id.

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