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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety and determinism are covered structurally. The description adds useful context beyond them: the data is US-priced, each entry carries a price check date and official sources, signaling freshness and provenance. It still says nothing about result size, ordering, or how 'documented access' for a feature is determined.

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 sentence with no filler, front-loading the geographic scope and the core data returned. It is a noun fragment rather than an action statement, which slightly weakens clarity but keeps it tight.

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 read-only, zero-required-parameter comparison tool with no output schema, the description covers the data domain, geographic scope, and provenance of the returned entries. It omits what the comparison output looks like and how many plans are returned, but those are minor gaps given the tool's simplicity.

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 all three optional filters (feature, provider, max_monthly_usd) are already documented in detail with examples and the annual-plan monthly-equivalent rule. The description adds no additional parameter semantics, so the baseline of 3 applies.

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 names a specific resource set: US prices, features and conditions for consumer AI subscriptions, and enumerates the covered providers (ChatGPT, Claude, Gemini/Google AI, Copilot). It clearly scopes to consumer subscription plans as opposed to model API prices, which hints at differentiation from get_model_prices, but it never states the comparison/list action explicitly and does not name siblings directly.

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?

There is no when-to-use guidance at all: nothing says to call this instead of get_model_prices, get_usage_limits or check_model_access, and no exclusions or prerequisites are given. The agent must infer from the phrase 'consumer AI subscriptions' that this is not an API-price tool.

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