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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, and the description adds genuinely useful field semantics beyond them: actual is null when no data, derived_target reflects criticality applied at the time, and explicit unit ranges (fci/asset_past_useful_life_pct 0-100, asset_condition_avg 0-100, risk_score_avg 0-25) plus 'Not money.' It does not cover not-found/error behavior, so not 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?

Four compact sentences, front-loaded with purpose and then field/unit clarifications; every sentence carries information an agent would otherwise have to guess.

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 and an existing safety annotation set, the description usefully explains return-value semantics and units for a single-read tool. It omits error/not-found behavior and the full return shape, which is a minor but real 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?

Only one parameter (id) with 100% schema description coverage, so the schema already carries the semantics and the description adds nothing new about it. Baseline 3 is correct.

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 plus scope: 'Get a single monthly Level of Service reading by ID.' This clearly distinguishes it from the list_los_status_snapshots sibling implied by the singular/by-ID framing, though it never names that sibling 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?

The description implies usage (fetch one reading when you have its ID) but gives no explicit when-to-use guidance, no prerequisites, and no mention of the list alternative for discovery. Adequate but leaves routing to inference.

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