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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior, and the description reinforces this with 'Read-only.' Beyond annotations, it discloses the data source (Ethereum mainnet ERC-8004 registry), the inclusion rule for the token index (only directory-listed projects, never the whole category or aggregate market cap), and the exact return shape. This is substantial behavioral detail that helps an agent trust and interpret the result.

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 well-structured with a front-loaded usage trigger, a compact explanation of what is included and excluded, and an inline return schema. It is slightly long but justified because there is no separate output schema in the definition and the exact semantics of the curated index need clarification.

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?

Given the tool has no output schema, the description compensates by embedding the JSON return structure. It also explains what each number represents, how the agent count is sourced, and what the token index intentionally excludes. Combined with the annotation set, nothing critical is missing for an agent to decide whether and how to invoke this tool.

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%, and both parameters (token_limit, response_format) have clear inline descriptions, defaults, bounds, and enums. The description does not need to add parameter syntax, and it does not; it focuses output semantics instead, which is appropriate. Baseline 3 is the right level because the schema already carries the parameter meaning.

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 identifies the tool's purpose: retrieving live ecosystem metrics, specifically the ERC-8004 registered-agent count and the curated Top Project Tokens index. It describes the resource and scope in enough detail to distinguish it from sibling tools like news, changes, or resource lookups, even though it does not name an alternative explicitly.

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 an explicit 'USE WHEN' condition: a current, citable figure is needed, and it draws a contrast with 'a number from an article of unknown age.' This gives clear context and a when-not-to-use signal, though it does not name an alternative sibling tool as the preferred replacement.

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