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

The annotations already declare non-read-only, non-idempotent, open-world behavior; the description goes further by disclosing the cost profile ("Consumes one autocomplete query and one API request"), which is the key behavioral fact an agent needs before calling. It does not, however, describe the response shape.

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?

Three short sentences, front-loaded with the action and scoped constraints; the cost sentence earns its place. The middle "useful to discover" sentence is somewhat expendable but not wasteful.

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 no output schema, the description does not explain what suggestions come back or any result limits, which is a minor gap for a simple fetch tool. Purpose, cost, and constraints are otherwise complete, and readOnlyHint=false is consistent with the stated quota consumption.

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 the schema already documents all four parameters, including the 1-60 prefix limit and the BCP-47 language detail. The description's only added parameter detail is the prefix length range, which is already in the schema.

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 (fetch autocomplete suggestions) plus the two target stores, and scopes it to a prefix. An agent can distinguish it from list_autocomplete_history (viewing past runs) 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?

Names a use case ("discover what users are searching for that starts with a given seed") but offers no when-not guidance and never mentions the obvious alternative, list_autocomplete_history, for retrieving prior results. Usage is implied rather than specified.

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