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

Goes well beyond the readOnlyHint annotation by disclosing that the inbox is refreshed from upstream feeds before listing (a network/side-effect behavior an agent must know about) and that view selects between inbox, saved, and history. It also adds a prompt-injection warning that article text is untrusted publisher data — valuable safety context. The only gap is it doesn't say what happens if the feed fetch fails.

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 what the tool returns, then narrowing options, then the refresh caveat, then the hand-off to read_article and the untrusted-data warning. Three sentences of dense, non-redundant information with no filler.

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 (title, source, date, summary, read/saved state), and it covers all eight parameters through schema plus narrative. An agent has everything needed to call it correctly on the first attempt.

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%, so baseline is 3, but the description adds genuine meaning: it clarifies the default view is the News-page inbox and explains the saved/read views in terms of user-facing concepts rather than enum labels. It does not expand on cursor or limit semantics beyond the schema.

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?

Opens with a specific verb+resource and describes exactly what is returned: 'Articles from the user's feeds, newest first... title, source, date, the feed's own summary, and whether the user has read or saved it.' It is clearly distinguishable from read_article and list_feeds, both of which it explicitly routes to.

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 concrete usage contexts: narrow by category/source/title words, use view "saved" for saved articles and "read" for history, and pass an item's url to read_article for full text. The refresh precondition ('unless refresh is false') is stated up front so the agent knows the side effect before calling.

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