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

No annotations are provided, so the description carries the full disclosure burden, and it does so well. It discloses the default query scope (authorized account's channels rather than the current kefu's own), the boundary that tag_id only covers labeled customers, the prohibition on empty-condition full pulls, pagination constraints (page from 0, page_size max 20), and that the return is customer UIDs for downstream calls. It loses one point only for not describing the response shape or error behavior, which for a no-annotation tool could have been richer.

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 long but every sentence carries decision-relevant information—no filler or tautology. It is front-loaded with purpose and default-scope behavior before the routing rules. The length is justified by the tool's complexity (13 parameters, many boundary conditions, multiple sibling relationships). It loses one point because the density could have been organized into clearer sections, but there is no wasted prose.

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 13-parameter tool with no annotations and no output schema, the description is remarkably complete. It covers core purpose, sibling routing (zhini_list_active_sessions, zhini_search_sessions + zhini_fetch_messages), default-scope semantics, ID-resolution prerequisites, natural-language tag boundaries, pagination constraints, and the downstream workflow (zhini_get_customer_profile or zhini_fetch_messages after obtaining UIDs). The return value (customer UIDs) is stated in the first sentence, compensating for the missing output schema.

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 description coverage is 100%, so the baseline is 3. The description goes beyond the schema by adding contextual usage semantics: it explicitly warns not to pass kfid/pic_kfids/channel_id unless the user states personal involvement or specifies a kefu/channel, and it documents the ID-resolution dependency (call zhini_search_tags/zhini_list_channels/zhini_list_kefu first) that the schema only hints at. This adds decision-relevant meaning the schema alone does not convey.

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 opens with a precise verb+resource statement: 搜索客户通讯录 (search customer address book) and enumerates every searchable criterion (name, phone, WeChat ID, kefu, responsible person, tag, channel, gender, contact type, time range) plus the output (customer UIDs). It actively distinguishes itself from siblings, explicitly stating it cannot be replaced by zhini_list_active_sessions for time-range all-user queries, so an agent can select it correctly.

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?

Exceptional when/when-not guidance. It specifies default scope behavior (all channels of the authorized account, not just the current kefu's handled customers), the exact conditions under which kfid/pic_kfids/channel_id should NOT be auto-passed, the natural-language tag boundary (don't auto-convert 用户/客户 to tag_id), routing to zhini_search_sessions + zhini_fetch_messages for chat-content conditions, ID-resolution prerequisites (zhini_search_tags, zhini_list_channels, zhini_list_kefu), multi-match confirmation, and pagination limits. This leaves no ambiguity about when to invoke it.

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