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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond that: the search scope is limited to the connected account's own contacts, results cap at 50 sorted by name plus a total match count, and it advises how to handle overflow. It stops short of richer detail but the added value is genuine.

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 trigger condition and use cases before mechanics (matching behavior, result cap). Every sentence carries information, though the paragraph is dense and slightly long for a single-parameter tool.

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?

An output schema exists, so return shape need not be described, yet the description still communicates the cap, ordering, and total count that matter for deciding whether to re-query. Combined with annotations and full schema coverage, an agent has everything needed to invoke this correctly.

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, but the description adds meaning the schema lacks: matching is case-insensitive and the query may be omitted to list contacts from the top. These are useful selection hints for an agent deciding how to construct the call.

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 ('search contacts in the Lemonvite address book') and immediately scopes it with three concrete intents (find someone, check if saved, get contact_ids). It is clearly distinguishable from siblings like lemonvite_list_guests, which it explicitly names as the alternative.

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 when to use it (user refers to people in their contact list) and routes to alternatives by name: lemonvite_invite_contacts and lemonvite_remove_contacts for downstream use of contact_ids, and lemonvite_list_guests for invitation rosters. No inference required.

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