web_open

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

With no annotations provided, the description carries full burden and does an excellent job: it states 'never touches the network', describes pagination of stored body, and specifies error return for unfetched handles. No contradictions.

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?

The description is concise with two sentences and an additional clarification sentence. It front-loads the main purpose and adds necessary detail without waste. Every sentence earns its place.

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?

Given that output schema exists, the description does not need to explain return values. It covers usage, prerequisites (cached document), behavior (no network), and error case. It feels complete for a pagination tool with these parameters.

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 baseline is 3. The description adds marginal value beyond schema: it explains handle format ('site~shorthash') and mentions defaults, but does not significantly enrich parameter understanding beyond what schema already provides.

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 clearly states the tool pages through an already-fetched document from the cache without re-fetching. It specifies the verb 'page through' and the resource 'cached document', and distinguishes itself from siblings web_fetch and web_search by noting it never touches the network.

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 description explicitly says 'Use this to read further pages of a page you previously fetched' and provides context on how to pass the handle from prior results. It also explains what happens if not fetched (returns error), which guides when not to use it. It does not explicitly mention alternatives but the context makes it clear.

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