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

With no annotations, the description carries the full burden and does so: it discloses re-verification of staff identity and mutual visibility at execution time, that no free quota or balance is deducted, that the read is audited, and that the assistant only surfaces the user's own App entry rather than contacting anyone. These are exactly the side-effect and safety facts an agent needs.

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 eligibility constraint and the prerequisite call, then the confirmation flow, then side effects. Dense but nearly every clause carries operational meaning; the final sentence about not contacting on the user's behalf is slightly tangential but still behaviorally relevant.

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 4-parameter, no-annotation, no-output-schema tool, the description covers prerequisites, the preview/confirm handshake, re-verification, billing impact, and the nature of the returned data. Only the exact shape of the returned contact payload is left implicit.

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 0%, so the description must compensate, and it does for the key parameters: preview defaults to true, previewHash is the token from the confirmed preview, consent must be true, and targetUserId is the verified target. It does not explain the hash's origin or format beyond the schema pattern, leaving a small gap.

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 makes clear this reads a staff member's authorized contact details under permission gating ('读取并审计', '外部MCP返回已授权联系方式'). It distinguishes itself from the prerequisite sibling get_contact_options, but never states the core purpose in one crisp sentence, so an agent must assemble it from several clauses.

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 prescribes the two-step flow: first call get_contact_options to verify the target and unlimited-count permission, default to preview, then after the person confirms re-call with the same params plus preview=false, previewHash and consent=true. The when-to-use and when-not-to-proceed conditions are both stated.

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