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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered by structured data. The description adds real behavior beyond that: the omit-topic fallback returns the union of all topics, and negotiation_coaching carries a usage restriction. It does not describe the shape of the returned reference material (format, size), which is the remaining gap.

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 sentences, front-loaded with the purpose, and the topic enumeration earns its length because it drives selection. There is mild repetition between the topic list and the follow-up 'Covers ...' sentence, which restates several entries rather than adding to them.

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 zero-required-parameter, single-enum reference tool with no output schema, the description covers what to fetch, what each value means, and the default behavior. The only missing piece is the form of the returned reference content, which an agent might want before deciding whether to fetch all topics at once.

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%, so the baseline is 3, but the description earns above that by annotating the enum values themselves — 'the standard level ladder', 'vesting patterns', 'how to resolve locations / job families / enums' — which the bare enum list does not convey. Some entries (enums, company_groups) are glossed only loosely.

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 names a specific verb and resource ('Get reference knowledge about the Levels.fyi data model') and immediately enumerates the eight topics, which signals a documentation/reference tool rather than an entity fetch. An agent can distinguish it from siblings like get-company or get-vesting-schedules without opening the schema.

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?

It gives an explicit conditional for a delicate topic ('negotiation_coaching ... use it only when the user asks for help negotiating') and states the default ('Omit "topic" to get every data-model topic'). It stops short of routing against near neighbors such as get-metric-explanation or get-vesting-schedules, so no cross-tool preference is stated.

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