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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: the response is structured data, it spans three currencies, and the BYOK note clarifies that AI usage billing is explicitly out of scope, preventing an agent from assuming this tool reports usage costs.

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?

Two sentences, front-loaded with the return payload before the BYOK caveat. The content list is dense but each clause maps to a distinct field set the caller would otherwise have to discover.

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 zero parameters, rich annotations and an output schema present, the description only needs to frame intent and scope, which it does. Nothing critical is missing, though a one-line pointer to a sibling (e.g. sign-up flows) would make it airtight.

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?

The tool takes zero parameters, so the baseline is 4 and there is no schema semantics for the description to supplement or contradict. No further parameter explanation is needed.

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 (retrieve current AI Data Stream plans) and enumerates exactly what the payload contains: monthly/annual prices in USD, GBP and EUR, tier inclusions, trial terms, extra seat cost and sign-up links. Against generic siblings like get_page and search_site, an agent can immediately tell this is the authoritative pricing source.

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 implied by the resource name and the enumerated contents, but there is no explicit when-to-use statement and no routing against alternatives (e.g. 'use this rather than scraping pricing via get_page'). Adequate but leaves selection to inference.

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