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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds genuinely new context beyond them: calling it 'costs nothing' (it does not consume credits) and that on the keyless connection it reports free sample rows left today. It does not discuss rate limits or caching, so a 4 rather than 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?

Three short sentences, front-loaded with purpose, then cost profile, then call triggers. No filler; every sentence carries a distinct piece of information.

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?

An output schema exists so return values need not be described. The description covers purpose, cost, trigger conditions, and the keyless-mode caveat — everything an agent needs to invoke it correctly.

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 api_key semantics are already documented (baseline 3). The description adds meaning about connection modes — the keyless /mcp/try path and what the key does/does not apply to — which helps an agent decide whether to pass it.

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 ('check how many Hunch credits are left on this key and how many have been used'), which is unambiguous against siblings like hunch_buy_credits or hunch_ask. An agent can identify the tool's function 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?

Gives explicit trigger conditions: 'Call it before a large batch, or when a judging tool reports texts were skipped for lack of credits.' It also clarifies the keyless /mcp/try behavior, so the agent knows which connection mode changes the result.

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