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

Annotations already establish read-only, idempotent, non-destructive, open-world behavior. The description adds substantial behavioral detail beyond them: empty periods with valid coverage return zero TPS and NOT_APPLICABLE/null success percentage, missing evidence returns an error rather than zero activity, and signature status is exposed explicitly in integrity.signed. It also clarifies that no anomaly or security verdict is provided.

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 description is front-loaded with the core purpose and scope, then packs return semantics, edge-case behavior, exclusions, and integrity notes into a small number of dense, useful sentences. There is 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?

For a read-only tool with no output schema and only two simple parameters, this description covers what is returned, how empty or missing data is handled, and what the tool is not. The only meaningful gap is the unexplained 'schema' parameter, and there is no explicit routing to sibling tools for related comparisons.

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 0%, so the description must carry parameter meaning. It explains the period parameter adequately ('today or yesterday UTC', default today) but does not describe the 'schema' parameter or its enum at all, leaving one of two parameters unexplained.

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 names a specific data resource (native fetchhub-4 transactions in blocks for today/yesterday UTC) and precisely lists what the tool returns: successful/failed/total counts, success percentage, and average TPS over 15-minute buckets. It also explicitly excludes related but different metrics such as peak TPS, capacity, messages, and mempool attempts, which helps distinguish it from sibling tools.

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?

Usage context is clear: the tool covers today or yesterday UTC and defaults to today. The description also provides useful exclusions ('Not peak TPS, capacity, messages, or mempool attempts'), but it does not name or route to specific sibling alternatives such as fet112.transaction_comparison or fet112.analytics_query.

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