Select the store

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

Annotations declare the safety/idempotency profile (readOnlyHint=false, idempotentHint=true, openWorldHint=true), so the bar is lower; the description still adds real value by disclosing that the selection is persisted and that a valid site session is required. The 'session expired -> open it on the site' clause hints at an out-of-band recovery step but is terse about what the agent must actually do.

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, zero filler: the action and persistence are front-loaded, and the prerequisite follows. Nothing is redundant with the title or schema.

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 values need no explanation, and the description covers the key prerequisite and failure mode for a stateful selection. It could say more about what happens when a store is already set or when the store_id is not in find_stores results, but the essentials are present.

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% and both parameters are documented in-schema, so the baseline of 3 applies. The description only reaffirms that the id originates from find_stores and doesn't add format or validation detail beyond the enum and id field already declared.

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 ('Selects the retailer's active store') plus the side effect ('remembers it'), and anchors the input to 'find_stores results', which cleanly separates it from the sibling find_stores (search) and list_stores (enumerate).

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?

Makes clear this is used with a store taken from find_stores output and states a prerequisite ('site session must be on this store') plus a recovery path for the 'session expired' case. It stops short of naming explicit when-not conditions or the alternative to use if the store is unknown.

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