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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuine value beyond that: it enumerates the returned fields and discloses a non-obvious domain behavior ('Federal amounts have no automatic provincial scaling').

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 sentences, front-loaded with the action and identifier requirement, then the return contents. The long field list is dense but earns its place because there is no output schema to document returns.

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 no output schema, the description appropriately compensates by enumerating what is returned and flags the federal/provincial scaling caveat. It is complete enough to invoke correctly for a simple single-record read, with only the absence of explicit sibling routing as a gap.

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 id parameter already documents the 12-character hex pattern with an example. The description's restatement of '12-character id' adds little beyond what the schema encodes, 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?

The description states a specific verb and resource ('Get one line item by its 12-character id'), which cleanly separates it from the list-style sibling search_records. It is clear about what is retrieved, though it does not name which sibling to use instead for other lookups.

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: the agent infers it should call this when it already holds a single 12-character id rather than searching. There is no explicit when-to-use, when-not-to-use, or named alternative (e.g., search_records) as there is in stronger sibling definitions.

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