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

Annotations already declare the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the bar is lower. The description still adds genuinely non-obvious behavior: a code is returned only where the brand has approved AI assistants, otherwise the store's vouchernaut.com page is returned instead — a data-gating condition an agent cannot infer from the schema. It doesn't discuss error behavior for an invalid/expired id, hence not a 5.

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?

A single front-loaded sentence leading with what is returned, followed by a compact enumeration of result shapes. The parenthetical about AI-assistant approval is dense but it is load-bearing information rather than filler; no sentence is wasted.

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?

An output schema exists, so return-value explanation is technically optional, yet the description uses that space to explain the shape variants and the AI-approval gating, which aids tool selection. For a one-parameter read-only tool this covers what an agent needs; only the relationship to detail-oriented siblings is unaddressed.

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 for the single `id` parameter is 100% and the schema already states it is 'An id from search' with length bounds. The description echoes the same constraint ('one result from search') without adding format, validity window, or expiry semantics. Baseline 3 applies when the schema fully carries parameter meaning.

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 specifies exactly what is returned: the full text of a single search result, with a concrete enumeration of result types (store codes/deals, product price and code, phone deals, buying guide). It implicitly positions itself against the `search` sibling by framing the input as 'one result from search'. The verb itself ('fetch') is only carried by the name/title, not restated, which keeps this just short of a 5.

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?

Usage is only implied: 'one result from search' tells the agent this is the drill-down step after `search`, and the schema's 'An id from search' reinforces that sequence. There is no explicit when-to-use vs. when-not, and no mention of the closer siblings like `get_store_offers`, `get_product`, or `check_deal` that also retrieve detail for a single entity.

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