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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds that results are 'normalized article cards', which is mild output-shape context, but says nothing about pagination, limits behavior, or coverage beyond the schema's max of 50.

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 sentences, zero filler, with the primary purpose front-loaded and the disambiguation second. Every sentence earns its place.

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?

Output schema exists so return values need not be explained, both parameters are documented in the schema, and the sibling disambiguation covers the main ambiguity. Only a small gap remains around result ordering and pagination.

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 the enum-like allowed category values are fully listed in the schema, so the schema carries parameter meaning. The description says category accepts 'the documented Learn sections' without adding format or default detail beyond the schema; baseline 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?

States a specific verb (fetch), resource (normalized educational article cards), and source (CoinGecko Learn), and explicitly names coingecko_news as the tool this is not. An agent can distinguish it from the sibling news tool without opening a 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?

Gives clear routing guidance: use coingecko_news for current market news rather than educational guides. It stops short of stating exclusions or prerequisites for this tool itself, but the alternative is named with the condition that selects it.

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