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 adds real value beyond that by disclosing the return shape ('bare record (with both field_x and field_x_raw values)'), which matters since no output schema exists. It does not cover error behavior for a missing id, keeping it short of a 5.

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?

Three short sentences with zero filler; the core purpose is front-loaded before the endpoint and return detail. Every sentence carries distinct 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?

For a simple two-parameter read tool with annotations covering safety and a description covering the return shape, the definition is essentially complete. Missing only minor operational detail such as not-found behavior, which is a small gap rather than a real omission.

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%, so both parameters are already documented (recordId as a hex string, objectKey as e.g. "object_1"). The description restates these in the endpoint template but adds no format, validation, or constraint detail beyond the schema, so baseline 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 a single record by id') and includes the exact API endpoint, which pins down semantics. 'Single record' implicitly distinguishes it from the sibling knack_list_records, though no sibling is named explicitly.

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 infers it should call this when it already has an objectKey and recordId. There is no explicit when-to-use, no exclusion for bulk retrieval (knack_list_records), and no guidance on when to prefer the generic knack_request.

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