fetch_order

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

No annotations exist, so the description carries the full burden, and it does meaningful work: it declares API credentials are required and discloses a real behavioral quirk — the spec marks `market_id` required for routing while the gateway currently resolves without it. It omits error behavior and rate limiting, but the auth and spec-vs-implementation disclosure is above baseline for an unannotated read tool.

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?

Three compact clauses, front-loaded with what the tool returns, then the parameter nuance and the auth note. No filler; the em-dash aside is informative rather than padding.

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 no output schema, the description usefully enumerates the returned fields, and with no annotations it covers auth and the parameter caveat. The main gap is sibling disambiguation against `get_order`, which matters given how many order-readers exist.

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%, so baseline is 3, but the description adds meaning beyond the schema: it explains why `market_id` matters (routing) and clarifies the conflict between the spec's requirement and actual gateway behavior, which the schema alone does not convey.

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?

Specific verb+resource ('Get a single order by its id') plus the return surface (status, fills, remaining size). It does not distinguish itself from the near-identical sibling `get_order` or from `fetch_orders`/`get_open_orders`, leaving an agent to guess which order-reader to call.

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 explicit guidance for when to supply `market_id` and flags the credential requirement, but offers no when-to-use guidance relative to `get_order`, `fetch_orders`, or `get_open_orders`. Usage is implied rather than routed.

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