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

readOnlyHint=true already establishes the safe-read profile, so the bar is lower. The description adds valuable return detail (line items keyed by line_id, dates, sub_total, tax, total, amount due) plus the exact REST endpoint, though it omits session-expiry/rate-limit or emptiness behavior.

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 compact sentences, front-loaded with the purpose and the return contents; the trailing API path is a minor extra but useful for developer alignment. No padding or repetition.

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 read-only, single-parameter tool with no output schema, the description compensates by enumerating the key returned fields. What an agent needs to invoke it correctly is largely present; minor gaps are session lifecycle and error/empty-state behavior.

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 the single parameter is already fully documented, including its provenance from checkfront_add_to_booking_session. The description adds no parameter-level detail beyond the schema, 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 ('Read') and resource ('booking session'), then clarifies the resource as the in-progress cart, which cleanly distinguishes it from the sibling checkfront_get_booking (a confirmed booking). An agent can tell what it returns without opening the 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?

Usage is implied rather than stated: 'in-progress cart' and the note that session_id comes from checkfront_add_to_booking_session suggest the retrieve-after-add flow. However, there is no explicit when-to-use vs an alternative (e.g., when to call this instead of checkfront_get_booking) and no stated prerequisites.

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