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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value by enumerating the exact returned fields (reward_xmr, difficulty, block_weight, orphan, etc.), which no structured field provides. It stops short of describing edge behavior (e.g. what happens if the hash is unknown), so not a full 5.

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?

Labeled 'When to use / Do not use / Returns' structure is front-loaded and scannable, and every sentence carries distinct information with no filler.

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 no output schema, the description compensates by listing the returned fields and identifying the two lookup modes. Nothing an agent needs to select or invoke the tool 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?

Schema coverage is 100%, so the baseline is 3. The description adds only the fact that the lookup can be done 'by height or by block hash', and the precedence rule ('block_hash... takes precedence over height') is already in the schema, so it adds no meaning beyond structured data.

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 ('One Monero block header, by height or by block hash') and explicitly distinguishes itself from xmr_get_recent_blocks and xmr_get_transaction. An agent can route correctly without opening any 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?

Provides explicit 'When to use' (confirming block for a tx, inspecting reward/difficulty/weight) and 'Do not use' clauses naming the two alternatives. Both positive and negative guidance are present.

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