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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint, but the description adds 'Read-only public research data. No account access, no order placement or fund transfers. Not investment advice.' This goes beyond the annotations by specifying data type and the absence of trading/auth features, fully aligning and enriching the behavioral profile.

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?

Single sentence with zero filler. Front-loads the core purpose, then packs routing and safety disclaimers in clean, scannable clauses. Every phrase 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?

For a read-only lookup tool with a full output schema and comprehensive annotations, the description covers purpose, sibling routing, edge-case hint (chain), and behavioral boundaries. Nothing essential for correct invocation is missing.

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%, so baseline is 3. The description adds meaningful insight by explaining that 'Chain fixes address clashes', which clarifies the chain parameter's purpose beyond the schema note. It also implies query flexibility ('ticker, name, or contract'), though most parameter details are left to the well-documented schema. This is a modest but real increment.

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?

Description explicitly states 'Single-target lookup: ticker, name, or contract→rows' – a specific verb, resource, and input types. It also distinguishes itself from siblings by naming search_coins for filtered lists and get_coin_rankings for boards, leaving no ambiguity about scope.

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?

Provides explicit routing: 'Filtered lists→search_coins. Boards→get_coin_rankings.' Also clarifies the chain parameter's role for address disambiguation and notes what is not included (no account access, no orders/funds), giving clear when-to-use and when-not-to-use context.

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