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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true and openWorldHint=false, so the safety profile is covered structurally. The description adds genuinely useful context beyond them: the data is static reference material cited from DataGenetics' 2012 study, and no user code is ever transmitted. It stops short of describing response shape or any freshness/staleness caveats for the cited data.

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?

The opening line is well front-loaded and the inline enumeration of `facts` and `patterns` is efficient. However the closing two sentences restate the same point twice ('the page makes them in your own browser... open the page for a code' and 'for a random code, send the user to the page'), and the raw URL plus parenthetical asides clutter what should be a short definition.

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, the description carries the burden of saying what comes back, and it does list the returned sections. It is not fully complete: the exact structure of `facts` versus `patterns` is not defined, so an agent knows the topics covered but not the precise shape of each field.

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 tool takes no parameters, so there is nothing the description needs to disambiguate; the schema provides an empty object with additionalProperties false. Baseline for a zero-parameter tool applies, with no gap to compensate for.

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?

Names a specific resource (door code lock facts) and enumerates the payload: `facts` (4 digits, shock per wrong guess, 8 tries then 15-minute lockout, guest codes), the ten most common four-digit codes, and `patterns` with brute-force timing. It is distinguishable from siblings like get_cctv_codes by scope, though it never explicitly names an alternative to contrast with.

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 an explicit when-not-to-use rule: the API does not generate or check codes, so for a random code the agent should send the user to the page instead of calling this tool. That is actionable routing guidance, but it is framed only around code generation and says nothing about when this tool is preferable to other reference tools.

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