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

Beyond the read-only annotation, the description adds meaningful context: the index is a daily z-score composite of transaction count, transfer volume, and fees; 50 denotes normal; history extends to the 2009 genesis block; and updates are daily. This helps the agent interpret the score and understand its computational basis.

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 three sentences long and front-loaded with the core return value. It then gives use-case guidance and update frequency without any filler. Every sentence contributes directly to tool understanding.

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 tool with one optional parameter and no output schema, the description is thorough: it lists all returned fields, explains the index scale and composition, and provides concrete usage scenarios. The schema covers the parameter, and annotations confirm safety, making the definition complete for an agent to select and invoke 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?

The main description does not mention the optional 'days' parameter, but the schema provides 100% coverage, including its effect (history series vs. snapshot) and the Gold tier requirement. The description adds no extra parameter meaning, so the baseline of 3 applies.

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 clearly states the tool returns a 0-100 Bitcoin network-activity index with specific output fields (score, trend, top_drivers, confidence, methodology_version). The verb 'returns' and the precise resource define its purpose unambiguously, distinguishing 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?

The description provides explicit 'Call when' scenarios covering user questions about surging/quiet activity, fee pressure, congestion, and timing decisions. It lacks explicit when-not-to-use or named alternatives, but the guidance is concrete and actionable within the context of a large sibling set.

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