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

Annotations only declare the mutation profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false); the description adds substantive context the annotations cannot convey — that the session is already live on return, that push_screen can pre-stage cards for users who haven't arrived, that offline re-push occurs on link open, and that hostUserId governs session ownership. Auth requirements and failure modes are still unstated.

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: purpose first, then parameters, then return value and lifecycle implications. Every clause carries information, though the run-on parameter paragraph could be split 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?

Covers the return shape ({url, session_id}) even though no output schema exists, and explains the session lifecycle and downstream consumers. For a four-parameter mutation tool with annotations already covering the safety profile, little is missing apart from error/edge-case behavior.

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, but the description adds real meaning beyond the schema: hostUserId is flagged as '强烈建议带' because session ownership and offline re-push depend on it, and targetId is framed as a care/business object. That dependency rationale is not present in the schema text.

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 pair ('为岗位生成画布链接 + 会话 ID') that no sibling duplicates, and immediately scopes it with the user-facing scenario ('看得见的界面'). An agent can distinguish this from canvas_action, get_session_log, or push_screen without opening any schema.

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?

Gives a clear trigger condition ('用户需要看得见的界面：看报告/看商品/做检测') and names the downstream siblings that consume its output (get_session_log / push_screen). It lacks an explicit 'when not to use' or a named alternative for the same task, so it stops short of a 5.

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