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

Annotations already cover read-only, idempotent and open-world semantics, and the description adds genuinely new behavioral context: it is free under an open-data carve-out, no payment is required, it makes no probability claim, and the payload carries provenance and freshness. It still says nothing about rate limits or staleness thresholds, keeping it below 5.

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 tight sentences, with the payload contents front-loaded before the pricing caveat. The emphasis words ('FREE', 'no probability claim is made') cost a little density but earn their place as routing signals.

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?

With an output schema present the description need not explain return values, and one required parameter plus rich annotations leave little burden. It is complete enough to call correctly, with only the asset-scope mismatch as a residual risk.

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 single `asset` parameter is fully documented in the schema, so the baseline is 3. The description's 'for BTC/ETH/SOL' framing actually narrows the asset scope relative to the schema's 'any symbol the venue universe lists', adding a mildly misleading gloss rather than useful meaning.

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 names a specific verb+resource (market snapshot) and enumerates the returned fields (fresh quote, derived mid and spread in bps, provenance, freshness), so an agent knows exactly what comes back. It does not, however, distinguish itself from near-neighbors such as tollbridge_marketcap or tollbridge_pricing, so it stops short of a 5.

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?

Usage is only implied: an agent can infer 'use this to get a spot quote' and the free/no-payment note helps route against paid siblings, but no alternative tool is named and no when-not-to-use condition is given.

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