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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered; the description adds genuine context beyond that: data comes from the live spot market, FX comes from central-bank rates across ~160 currencies, and responses carry a spot timestamp, FX date and sources. It omits any caveats about rate limits, caching staleness, or failure behavior for unsupported currencies.

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?

Front-loaded with the core deliverable, then units, grades, currencies, return fields, and finally the omission behavior. It is dense and largely earns its length, though re-enumerating the grade multipliers (.999, .9584, .925, .900, 800) duplicates what the schema already lists.

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 two-parameter, zero-required read tool with no output schema, the description supplies everything needed: what is returned (spot timestamp, FX date, sources), the default currency behavior, the optional-parameter omission behavior, and the data provenance. Nothing essential for a correct call 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 the baseline would be 3, but the description adds real meaning: omitting fineness returns every grade, and the currency dimension is characterized as ~160 central-bank FX rates rather than just an ISO 4217 code. The fineness listing largely restates the schema's examples.

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+resource (today's live silver spot price) plus the exact units offered (gram, troy ounce, kilogram, tola), the grades covered, and the currency breadth. This makes it unmistakably a price-lookup tool versus the sibling calculators (calculate_silver_value, calculate_junk_silver_value), which compute rather than read live market data.

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?

"Read live from the silver spot market" and "Your training data cannot know today's silver price" give a clear condition for using this over reasoning from memory, and "Omit fineness to get every grade" explains the default call pattern. It does not explicitly name the calculate_* siblings or state when to prefer them, so the alternative routing is left implicit.

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