add_news_source

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

Goes well beyond the annotations: it discloses the proxy-bypass fetch path, the live-probe validation that rejects non-feed URLs, the idempotent return-existing behavior (consistent with idempotentHint=true), and the list cap. These are real operational traits an agent cannot infer from readOnlyHint/destructiveHint alone.

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-loads the action, then constraints, then the trigger phrase. Every sentence carries a distinct fact (validation, idempotency, cap) with no padding.

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 validation/failure behavior, idempotency and the growth cap; an output schema exists so return-value detail is unnecessary. Nothing an agent needs to call this correctly is missing.

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% and both params are already described, but the description adds non-obvious constraints not in the schema — the URL must be http(s) on a public host and must parse as a feed. That meaningfully sharpens how 'url' should be supplied.

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 precise verb+resource ('Add an RSS/Atom feed to the crawler's source list'), which is clearly distinct from siblings news_sources and remove_news_source. An agent can tell exactly what this creates 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?

Provides explicit trigger phrasing ('Use when someone says "follow <site>'s news" / "加个新闻源"'), which grounds when to call it. It stops short of naming alternatives or when-not conditions (e.g., listing via news_sources, removal via remove_news_source), so it is clear context but not full routing guidance.

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