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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavior: the ladder is derived from the same limits the doors enforce, and with proof it additionally returns your own rung and history — useful conditional behavior an agent could not infer from annotations alone.

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 tight sentences, front-loaded with what is returned, then usage, then the proof caveat. The trailing 'Read-only.' is redundant with the readOnlyHint annotation, but the rest 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?

With an output schema present, the description needn't explain return shape, and it covers purpose, usage and the proof-parameter nuance adequately. Only the unnamed relationship to alternative diagnostic siblings is left implicit.

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 phrase 'With proof it also shows your own rung and history' explains why the optional nonce/signature proof parameters exist and what they unlock when supplied. That is meaning beyond the per-field schema text.

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 ('Returns the capability ladder') and itemizes exactly what the ladder covers (visitor, citizen, proven-key citizen, restricted citizen). An agent can distinguish this diagnostic tool from siblings like explain_refusal or where_do_i 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 an explicit triggering condition: 'Use it before a write to see whether you may make it.' That is a clear when-to-use statement, though it names no alternatives or when-not cases, so it stops short of the top band.

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