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

Annotations cover the safety profile (readOnlyHint, openWorldHint, destructiveHint=false), and the description adds substantial context beyond them: expected latency (3-6 seconds), the x402 payment requirement, the no-charge-on-failure guarantee, and the login-page limitation. This is exactly the extra behavioral detail the annotations cannot convey.

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?

Four tight sentences, each carrying distinct load: capability, routing rule, constraint, and cost/failure behavior. The most decision-relevant facts (scope, sibling routing) are front-loaded with zero 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?

Although there is no output schema, the description itself describes the return shape ({url, summary, key_points}), plus timing, cost, and failure semantics. For a single-parameter read tool, nothing an agent needs to invoke it 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?

Only one parameter, and the schema already documents it fully at 100% coverage, so the baseline is 3. The description reinforces the accessibility constraint (public pages only, invalid URLs fail) which slightly sharpens the url semantics, though it largely restates what the schema field already says about private/local addresses.

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 (condenses) and resource (one public web page) plus the concrete output form: an 80-word summary with up to 4 key points. It explicitly distinguishes itself from the closest sibling, bob_extract, so an agent can choose without opening either 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?

Gives an explicit selection rule ('when you want the gist') and names the alternative with its contrasting use ('use bob_extract to get the page's own text instead'). It also states a hard exclusion (pages needing login cannot be read), which is exactly the when-not guidance an agent needs.

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