Get the current price

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

With annotations already covering the safety profile (readOnly, idempotent, openWorld, non-destructive), the description still adds substantial context: the required `market:read` scope, a hard 60/hour limit shared across the whole `venue-public` group, and the reason (it serves a cached copy good for the hour). These are exactly the operational facts an agent needs and none are derivable from the annotations.

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?

Purpose is front-loaded in the first sentence and the scope/rate-limit facts follow logically. The rate limit is stated twice ('60 requests per hour' then 'Sixty an hour') for rhetorical emphasis, which is mildly redundant and slightly inflates length, but the rationale sentence earns its place.

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-param read with no output schema, the definition covers purpose, authorization, and rate limits thoroughly. It does not describe the shape of the returned price (field names, timestamp, precision), which an agent guessing blindly might want, but the annotations already certify this as a safe idempotent read, so the gap is minor.

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% with only two parameters, and the schema already documents both venue (with an enum and the 'market half of the name' note) and symbol. The description restates 'one symbol on one venue' without adding format, casing, or enum guidance beyond the schema, so the baseline of 3 applies.

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 precisely what is returned: the current price for one symbol on one venue. The resource and cardinality ('one symbol on one venue') are unambiguous, and no sibling tool returns prices, so confusion is unlikely. It stops short of naming or contrasting any sibling explicitly, which keeps it out of 5 territory.

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?

Gives real routing advice: 'Read an instrument list once and keep it' and, for higher-frequency needs, 'read the venue's own public API' instead. That is an explicit when-not plus an alternative, which is rare and valuable. It does not frame usage relative to the MCP siblings (e.g. list_instruments), so it falls just short of a 5.

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