list_customers

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

Annotations already declare readOnlyHint=true, so the description isn't required to state safety. It adds value by disclosing that the tool returns aggregate data (order count and total spent) and that the fields param can be used to request only needed fields. This provides behavioral context about return contents beyond the read-only annotation.

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?

The description is two sentences long and front-loaded with the core action and resource. The first sentence states what the tool does; the second adds a useful usage tip about the fields parameter. Every sentence serves a purpose with no fluff.

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 7-parameter list tool with no output schema, the description covers the essential behavior: filtering and return of per-customer aggregates. It does not explain pagination or sorting, but those are documented in the schema. The return data is partially described, which is adequate given the schema's field listing.

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 input schema has 100% description coverage, so the baseline is 3. The description mentions filtering by name, email, or role, which maps to search and role parameters, but it adds no syntax or format details beyond what the schema already provides. It does slightly reinforce the purpose of fields but not substantially.

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 clearly states a specific action ('Search and filter') on a specific resource ('customers'), and distinguishes from siblings like list_products or get_customer by noting it returns order count and total spent per customer. It unambiguously identifies this as a list/search tool for customers.

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?

The description implies usage for searching/filtering customers but does not explicitly state when to use this vs get_customer, create_customer, or update_customer. The presence of sibling tools suggests a listing/search context, but there is no explicit 'when not to use' or alternative guidance beyond the implied purpose.

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