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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful behavioral scope: this is the only source for the data, along with concrete return semantics including the posture values and ratio formula. No contradiction with 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?

Front-loaded with a strong task statement and immediately useful examples and exclusions. Slight redundancy between 'THE tool' and 'the only tool that has it', plus the long examples list, keeps it from a 5, but every sentence earns its place.

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 no output schema, the description fully covers what an agent needs: when to call, what it returns, and how the effective ratio is computed. No call-critical information 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?

The single parameter companyId is fully documented in the schema, so the description does not need to add parameter-level detail. It implies company scoping via 'this company's' but does not add syntax or format conventions; 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 and resource ('get CAC strategy') and enumerates exact output: posture values and effective ratio. The examples and explicit exclusion of get_company and get_financial_summary distinguish it from nearby lookup siblings.

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?

Explicitly says to use for any question about CAC strategy or LTV:CAC ratio, and names get_company and get_financial_summary as alternatives not to use because the data is not there. Also instructs the agent to call this tool directly, leaving no routing ambiguity.

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