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

Annotations already indicate readOnlyHint, idempotentHint, and non-destructiveness. The description adds valuable behavioral detail beyond the annotations: a 50-match limit, the kinds of data returned (asset class, services, pricing tier), and the guarantees that it is free, read-only, and does not trigger payment or provide live prices.

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 two sentences with no filler. It front-loads the main purpose, then packs the crucial constraints (free, read-only, no live prices, no payment) into a compact second sentence. Every clause adds useful information.

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 rich annotations, a fully described input schema, and an output schema, the description provides everything an agent needs to decide whether and how to call it. It covers the catalog scope, result-size cap, and safety guarantees, so no critical context 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 description coverage is 100%, so the input schema fully describes both the query parameter and the asset_class filter. The description does not add new parameter-level meaning beyond the schema, so it earns the baseline score for schema-documented parameters.

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 uses the specific verb 'Discover' with a clearly defined resource: supported crypto, equity, FX, and metal symbols. It also states what the tool returns (catalog matches with asset class, services, pricing tier) and distinguishes itself from live market data and payment-triggering tools by explicitly saying it never returns live prices or starts payment.

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 clear when-to-use context: 'before using the paid HTTP API.' It also gives exclusions by noting the tool is free, read-only, and never returns live prices or starts payment. It does not name sibling tools or explicitly contrast list_instruments/search, but the usage context is strong enough to guide selection.

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