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

Beyond the annotations (readOnly, openWorld, idempotent, non-destructive), the description discloses meaningful behavioral details: newest-first ordering, deduplication, optional date filtering, bounded plain text, and the discovery ladder when given a site URL. It also reveals that the result reports how the URL resolved, which is useful for agent interpretation. No contradiction with annotations.

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?

Three sentences deliver a complete mental model: what is returned, how items are ordered and filtered, URL flexibility and resolution reporting, and the intended use case. Every clause earns its place; there is no repetition of schema defaults or annotation trivia.

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?

With no output schema, the description compensates by enumerating the returned fields and noting the resolution message. It covers the main parameters (url, since, task_context, bounded text) and the tool's behavior. The only small gap is that 'limit' is not mentioned in the description, but its schema default and bounds make it fairly self-explanatory.

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 80%, so the baseline is 3. The description adds real value beyond the schema: it explains that url may be a feed URL or a site undergoing discovery, that 'since' filters by published or updated date, that text is bounded, and that task_context tunes the result. This goes beyond the schema's individual descriptions, justifying a 4.

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 specific verb ('Read') and resource ('a feed'), then enumerates the exact output shape (id, title, url, published, authors, categories, lead, plain text). It also states ordering and deduplication, making the tool's purpose unmistakable and implicitly distinguishing it from siblings like feed_find and news_search.

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?

The final sentence, 'Use for "what is new on X"', is a clear trigger for when to invoke this tool. It also explains that url can be a feed URL or a site URL, so the discovery behavior is contextualized. It does not explicitly contrast with siblings or state when not to use it, 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.