books_get_customer

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

No annotations are provided, so the description carries the full burden. It says 'Get detailed information' and lists return fields, indicating a read operation, but it does not explicitly state that the tool makes no modifications, requires specific permissions, or handles missing IDs. The read-only nature is implied by the verb 'Get' and the schema's readOnlyHint and idempotentHint (though these are not in the annotations section). This is acceptable but not exceptional.

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 concise, two sentences plus a related-tools line. It leads with the purpose, immediately followed by the return content, and then provides useful cross-references. No filler or redundant information.

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?

The tool is simple (one parameter, no output schema, no nested objects). The description explains what is returned (contact details, addresses, account status) and how to obtain the ID. It does not specify error behavior (e.g., 404 if not found) or authorization requirements, which could be useful but are not critical for such a straightforward lookup tool.

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 single parameter customer_id is fully documented in the schema with description 'Unique customer ID (get from books_get_customers).' The tool description reinforces this by saying 'by ID' and pointing to books_get_customers in the related tools. Since schema coverage is 100%, the description adds marginal value beyond what the schema already provides, so a baseline score of 3 is appropriate.

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 the tool's function: 'Get detailed information for a specific customer from Books by ID.' It specifies the resource (customer), the action (get), and the key identifier (ID), and it distinguishes it from sibling tools like books_get_customers (which lists customers) and mutation tools (create/update/delete). The return contents are also detailed: 'complete customer profile including contact details, billing/shipping addresses, and account status.'

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 provides clear guidance on related tools: 'books_get_customers (to find IDs), books_create_invoice (to bill customer), books_create_payment (to record payments).' This tells the agent when to use alternatives for finding IDs or taking actions, implying that this tool is for retrieving a single customer's details. It doesn't explicitly say 'use this when you need a customer profile,' but the context is sufficient for a straightforward get-by-ID operation.

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