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

Annotations already cover read-only, idempotent, non-destructive behavior, but the description adds meaningful context beyond them: nothing is stored, prices come from CoinGecko, the arithmetic is on past prices, and the response must include the stamp, sources, and not-advice line. It also clarifies that no coin recommendation or investment advice is involved.

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 relatively short but structurally awkward: the main idea is buried after an initial question fragment, and the final instruction about the stamp, sources, and not-advice line may overlap with output handling. It is not bloated, but it is not tightly front-loaded either.

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 that an output schema exists and annotations cover safety, the description supplies the important remaining context: the data source, the no-storage behavior, the disclaimer constraints, and how holdings are interpreted. It is nearly complete for correct invocation, with only minor gaps around malformed inputs or unsupported coins.

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 both the holdings paste format and the optional since date are already documented in the schema. The description reinforces the paste-style input with an inline date example, but it does not add syntax, validation, or fallback behavior beyond what the schema provides.

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 outcome (comparing a pasted portfolio against Bitcoin) and explains the pricing basis (then and now, from CoinGecko). It is clearly distinguishable from siblings such as crypto_today or compare_stocks, though the phrasing is slightly indirect and starts with a question rather than a direct verb.

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 implied: call this when a user provides a portfolio paste and wants to know whether it beat Bitcoin. There is no explicit statement of when not to use it or which sibling tool to prefer for related questions, so guidance is adequate but not strong.

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