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

Annotations already declare readOnly/idempotent/non-destructive, so the safety bar is met; the description adds real non-obvious behavior — the served=false-plus-tier fallback path for chains that are not live yet, plus the returned field names in the absence of an output schema. It stops short of covering data freshness/caching or failure modes, keeping it at 4.

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?

Front-loaded with purpose, then use/do-not-use, then returns; the labeled structure makes it scannable. The return-field list is slightly dense but earns its place since there is no output schema to carry it.

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 single-enum, read-only status tool with no output schema, the description supplies purpose, routing exclusions, return fields and the one notable edge case — everything an agent needs to select and call 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 description coverage is 100% and the single enum parameter is fully documented in the schema, so the description adds no param-level detail (no enumeration, no defaults, no notes on invalid ids). Baseline 3 is correct when the schema already carries the parameter semantics.

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 resource and scope ('Live run-time state of one chain's node') and enumerates the exact quantities it exposes (height, peer count, mempool depth, client version), which separates it cleanly from per-chain block/transaction/node-status siblings.

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?

Explicit 'When to use' framing plus an explicit 'Do not use' list naming three alternatives (btc_get_fee_rates, btc_get_transaction, zec_get_pool_status) with the condition for each. Nothing is left to inference.

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