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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint, so the bar is lower. The description adds value beyond annotations: it discloses the per-call cost ($0.02/call), the wallet-required payment mechanism (MPP / npx agent-index or prepaid credits), and that the hosted connector holds no wallet — auth/payment context annotations never provide. This meaningfully enriches the behavioral profile.

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 core function and output shape are front-loaded in the first clause, and the operational/payment details are gated to the end. The auth block is long but earns its place because agents must know how to fund the call. Slightly verbose overall, but each sentence carries information.

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?

For a 4-param, read-only search tool with a provided output schema, the description covers the essentials: expected return shape ({ query, count, results }), freshness semantics, the web-index-lags selection cue, and the required payment path. Nothing an agent needs to call it successfully (besides what structured fields already carry) 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%, so the baseline is 3. The description contributes minor param value by mapping freshness to the same filter codes as web search (pd/pw/pm/py), but the input schema already encodes those exact values and the count range, so the description mostly reinforces rather than adds new meaning. A 3 is appropriate.

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 and resource ('Live news search') and enumerates exact output fields (title, URL, snippet, age, source, breaking flag). It distinguishes itself from the sibling web.search by noting it is 'optimized for current-events queries where the web index lags', which an agent can use to pick between tools 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 a clear when-to-use signal: current-events queries where the web index lags, and discloses it shares the web search freshness filter. It does not name the exact siblings (web.search / web.answer) or state an explicit when-not condition, so the guidance is useful but stops short of a direct alternative-selection rule.

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