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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds value beyond them by disclosing the payload shape — each instrument ships with its gccbrokers.com page link — which matters since there is no output schema.

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?

A single front-loaded sentence names the resource and its contents, followed by a short filtering clause. No filler, though the parenthetical category list partly duplicates the enum already in the schema.

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 read-only listing tool whose annotations cover the safety profile and whose schema fully documents both parameters, the description supplies the return contents and the category filter. Nothing critical is missing, though a pointer to get_instrument for single lookups would close the last gap.

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 both parameters enumerated and documented (category enum, language enum with default en). The description only echoes the category filter, adding no format or behavior beyond what the schema already states, so the baseline 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?

Specific verb ('Lists') plus resource ('instruments GCC Brokers offers') and an explicit enumeration of the asset classes covered, so the agent knows exactly what comes back. It does not, however, distinguish itself from the singular sibling get_instrument, leaving that routing to be inferred.

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?

'Filter by category' implies how to narrow results, but there is no statement of when to call this versus get_instrument or get_prices, and no exclusions or prerequisites. Usage is implied rather than taught.

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