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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the description's 'read-only, no network, no stored state' largely restates them. What it genuinely adds beyond structured data are concrete operational limits (64 KB JSON input, 1 s per call, 1 MB result) and the determinism guarantee, which are useful for call planning.

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 structure is excellent — purpose first, then When / Not for / Side effects / Deterministic / Limits — and every sentence carries information. The only cost is full duplication in Spanish and English, which roughly doubles length for a single-parameter tool.

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 explained, and the description still adds limits, determinism, side-effect profile and the sibling alternative. For a one-parameter decoder, nothing an agent needs to call it correctly 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?

With a single parameter at 100% schema description coverage, the schema already documents the input fully (type, maxLength 1023, example). The description adds no syntax, casing, or edge-case guidance (e.g., handling of uppercase or mixed-case strings) beyond the schema, so the baseline 3 applies.

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 EN text states a specific verb and resource ('Decodes a Bech32 or Bech32m string'), plus the extra behaviors of variant detection and the returned fields (prefix, 5-bit words, 8-bit data). It explicitly names the sibling it is not (bech32-encode), so an agent can distinguish the two without opening schemas.

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?

There is an explicit 'When' block, a 'Not for' block and a named alternative (bech32-encode), which is more than most definitions offer. However, the 'When' line says the tool applies when bytes or text must be converted 'to or from this encoding', which overlaps with the encoding direction it just excluded — a small internal ambiguity about directionality.

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