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

With no annotations, the description carries the full burden, and it does disclose the important non-obvious trait: this is a paid call at $0.015 USDC on Base, settled in-band via x402 _meta. It also gives a free-ish bypass (day pass) and a mirror REST endpoint. It omits failure semantics that matter for a paid tool — whether payment is captured if the call errors, retry/refund behavior, and rate limits.

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, front-loaded with a bracketed category tag and the core verb-less but specific statement of what is returned, followed by payment mechanics. Dense but every clause carries information; minor crowding from the inline endpoint URL and package reference.

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?

No output schema and no annotations, so the description does the work — it effectively names the return fields and fully explains the payment path plus a no-payment alternative. Gaps remain around error/insufficient-payment behavior and the exact symbol convention, which are the two things an agent could plausibly get wrong.

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 50%. The `pass` parameter is well documented in the schema itself, and the description adds no further detail. For the required `symbol`, the schema only supplies a character pattern with no description; the description clarifies it is 'one coin' and appears as a path segment in the REST URL, but never states whether it is an exchange ticker ('BTC'), a case convention, or another identifier scheme.

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?

Names the resource precisely (value-capture score for a single coin) and enumerates what the score is composed of: net supply, holder yield, usage class, burn-versus-held class, unlock overhang. It does not explicitly contrast itself with the closely related siblings get_value_screen and get_value_history, so the agent must infer that 'one coin' means single-symbol versus a screening/history tool.

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: this is the per-coin lookup, and the pass parameter skips per-call payment. There is no explicit statement of when to prefer get_value_screen, get_value_history, or get_coin, and no guidance on what to do if the spend policy rejects the payment, despite check_spend_policy / should_i_pay being siblings.

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