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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description goes beyond that by disclosing what the read returns – contact details plus the customer's bookings as codes with created dates – which is genuinely useful behavioral context given no output schema exists.

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 short sentences, front-loaded with the substantive payload description, followed by the API mapping. Every fragment carries information; nothing is padded.

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 only one parameter and no output schema, the description usefully compensates by naming the returned fields (contact details, booking codes, created dates). What is missing is error/not-found behavior and any pagination note for the embedded bookings list, which slightly caps this below 5.

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?

Single parameter with 100% schema description coverage, so the schema already documents that customer_id accepts an id or customer code. The description adds no additional parameter meaning (no format rules, no alternate lookup keys beyond what the schema lists), 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?

States a specific verb and resource ('Fetch one customer's contact details and their bookings') with scope precision ('one customer'), which cleanly separates it from the plural sibling checkfront_search_customers and checkfront_list_bookings. The added endpoint reference reinforces exactly what is being retrieved.

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?

Usage is only implied: an agent can infer this is the tool to call when it already has a customer id/code rather than needing to search. However, there is no explicit when-to-use or when-not guidance (e.g., 'use search_customers first if you only have a name or email'), so the routing decision against checkfront_search_customers is left to inference.

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