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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's added value is the data-availability constraint (history from 2026-09-20 onward only) and the unit semantics (measure's own unit, not money) - both genuine behavioral context beyond the annotations.

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?

A single sentence, front-loaded with the operation and the returned content, with the two useful caveats (unit, date range) appended. No filler or redundancy.

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 one-parameter, read-only getter with full annotations and 100% schema coverage, this is close to complete; the unit and history-window notes close the main gaps. It could go further by contrasting with the adjacent get_los_* / list_los_targets_history tools, but nothing needed to call it correctly is missing.

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 coverage is 100% with a single well-documented uuid 'id' parameter, so the schema already does the work. The description's 'by ID' adds no syntax, format, or lookup nuance beyond what the schema states; baseline 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?

States a specific verb (Get) and resource (a single LoS targets history entry by ID), and even enumerates what the entry contains (target, minimum, stretch goal, effective_date). The word 'single ... by ID' implicitly separates it from the list_los_targets_history sibling, but it never explicitly contrasts itself with the other get_los_* siblings (measure, measurement, proposed_target).

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 'by ID' framing implies a point lookup rather than a listing, and the note that history exists from 2026-09-20 onward gives a usable data-availability boundary. However, it never states when to reach for this versus list_los_targets_history or get_los_measure, leaving the routing to inference.

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