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

With no annotations, the description carries the full burden. It discloses the confirmation-before-execution step, but says nothing about auth requirements (api_key/token are only implied), whether the purchase is reversible, or failure behavior for a financial mutation.

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-loads the core action, but the opening sentence is repeated word-for-word and the @return tag ('a json object') is filler. The @param block is structured but the duplication wastes space.

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?

Covers the parameters well, but for a financial mutation with no annotations and no output schema it omits return structure (just 'a json object'), auth expectations, and failure/irreversibility details an agent would want.

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 0%, so the description must compensate, and it does: it documents all four params via @param tags. Notably it clarifies account_fk is a database int ID (not an address) that may not be 0, and that token comes from /access/login — meaningful value beyond the bare schema.

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 (Purchases), resource (digital asset), and source of funds (account's FIAT balance). This distinguishes it from siblings like account_sell or crypto_swap, though the sentence is duplicated verbatim, adding no extra value.

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 'Confirm (yes/no) before executing' instruction gives a usable workflow cue, and the fiat-to-asset framing implies when it applies. However, it never states when to prefer this over account_sell, crypto_swap, or crypto_spend, so alternatives are left to inference.

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