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

Annotations already declare this a read-only, idempotent, non-destructive, closed-world lookup, so the safety profile is covered. The description adds genuinely useful context beyond that: results are specific to the Standard account, trading hours are normalized to UTC, and swap figures are split long/short with multi-night rollover days. It does not say how unknown or ambiguous instrument names are handled.

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, zero waste. The returned-field inventory is front-loaded, and with no output schema present every enumerated field earns its place by telling the agent what it will receive.

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 exists, so the description must carry the return-value burden — and it does by naming the spec fields and their units (UTC hours). Account scope, alias acceptance, and the language parameter (fully documented in the schema) are all covered; nothing needed to call it correctly is missing.

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 goes further by listing accepted alias forms ('EUR/USD', 'XAUUSD', 'gold', 'Nasdaq', 'bitcoin') that the schema's own examples ('EURUSD', 'gold', 'US30') do not cover. This materially reduces the chance of a failed lookup due to formatting.

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+resource (trading specifications for ONE instrument) and enumerates exactly what is returned: contract size, lot min/max/step, margin, swap long/short, rollover days, weekly hours in UTC. The singular scope cleanly separates it from the sibling list_instruments.

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 'one instrument' scoping implicitly routes the agent here for a single-symbol lookup rather than a catalog listing, and 'as clients trade it on the Standard account' establishes the account context. It never names an alternative tool or states a when-not condition, so it falls 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.