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

Annotations only declare readOnlyHint=true; the description adds real behavioral context beyond that — the following feed requires authentication and will typically return empty, and attachType must be paired with attachId. It does not discuss pagination via cursor or result ordering, which keeps it short of a 5.

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?

Purpose and default are front-loaded in the first clause, with alternatives after. It is dense and telegraphic with arrow notation, which is efficient but slightly harder to parse than plain sentences.

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 purpose, default behavior, login precondition, related-object filtering, and the downstream tools to call for details or signups — everything an agent needs to pick and drive this tool. With no output schema, only return-shape detail is absent, which is minor.

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 already 100%, including the feed enum semantics and the attachType/attachId pairing, so the description largely restates structured data. The pairing hint is reinforced but no new syntax or format is added, so baseline 3 applies.

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 (读官方资讯/活动/政策) and immediately scopes it away from user-generated content by naming list_moments_feed and search_moments as the alternative. An agent can distinguish this from any of the many list_* siblings without opening the 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?

Explicit guidance: recommend is the default, following requires login and is usually empty, related-content lookups use attachType+attachId, and follow-up paths are spelled out (get_post→get_activity/get_product, 报名→get_signup_activity). It names the alternatives and the conditions that select them.

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