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

Annotations only cover the safety profile (idempotentHint=true, readOnlyHint=false), and the description adds genuinely useful behavior: the call costs 0.0025 test USDC on eip155:84532 and the idempotencyKey must be preserved across retries. This explains why readOnlyHint is false (a paid call) and tells the agent how to retry safely, though it omits failure/refund behavior.

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, front-loaded sentences with no filler; the cost and retry constraints are stated directly. Slightly terse for the ambiguity it leaves unresolved, but structurally clean.

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 paid tool with no output schema and a positional, undocumented params array, the description should explain the array's positional semantics and what the header response contains. Neither is present, leaving the agent likely to mis-order the arguments on a call that costs money.

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 50% and the uncovered half is the critical part: a positional 2-item array of [64-hex block hash, boolean] with no descriptions. The description only echoes the idempotencyKey retry rule already stated in the schema and never explains that the boolean is a verbose flag or what order the array items take.

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?

"Read getblockheader from Bitcoin" essentially restates the tool name; it never says that a block header is returned for a given block hash, nor distinguishes it from siblings like bitcoin_getblock (full block) or bitcoin_getbestblockhash. The chain identifier (bip122:0000...d668) is the only added specificity, which is metadata rather than purpose.

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 no statement of when to choose this over bitcoin_getblock, bitcoin_getblockhash, or bitcoin_getbestblockhash, and no prerequisites beyond the cost note. The retry/idempotency sentence describes a mechanic, not usage selection, so an agent has no routing guidance.

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