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

Annotations already declare readOnlyHint and openWorldHint, so the read-only, network-fetching nature is covered. The description adds no behavioral context beyond that, such as pagination, rate limits, or data granularity.

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?

Two concise sentences: first states the action and retrieval method, second gives the alternative. Front-loaded with no waste.

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 chart-series tool with a full output schema and rich annotations, the description supplies the essential routing. It could mention pagination or data-point intervals, but given the output schema exists, that would be redundant. Nearly complete.

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 100%, so the schema already documents kind, limit, and range with allowed values. The description names kind and range but adds no syntax or format details beyond the schema. Baseline 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?

States a specific verb (Fetch) and resource (global cryptocurrency chart-series data) with the scoping parameters (kind and range) named. The sibling-comparison is not exact; it points to coingecko_global as the variant for a current snapshot, which differentiates the tool's role as historical chart series.

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?

Explicitly routes the agent: use coingecko_global for the current global market snapshot, implying this tool is for chart-series over time. Lacks explicit exclusions or prerequisites, but the routing is clear.

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