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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds meaningful behavioral detail beyond annotations, especially the 'first 50 transaction IDs' limit, which warns the agent that the result is intentionally partial.

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?

One efficient sentence communicates the resource, lookup method, and return contents. There is no filler or repetition of the schema, and the most important scoping detail ('header data') is front-loaded.

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 one required parameter, a well-documented schema, rich annotations, and an output schema, the description fills the remaining gaps: what kind of data is returned and the 50-transaction limit. Nothing essential is missing for correct invocation.

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 schema already documents the single parameter with 100% coverage, including the height-or-hash format. The description's 'by height or hash' adds little beyond the schema, so the baseline score of 3 is appropriate.

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 description states a specific verb and resource: 'Header data of a block by height or hash' and enumerates the exact content (time, confirmations, transaction count, first 50 IDs). This clearly distinguishes it from sibling tools like get_transaction and get_chain_status.

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?

The description clearly indicates this tool is for retrieving block header data by height or hash. It does not explicitly name alternatives or exclusion conditions, but the context is unambiguous for an agent deciding to fetch block-level data.

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