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

Annotations already cover read-only/idempotent behaviorags. The description adds meaningful scope details: it covers brokerage and crypto-exchange accounts, excludes bank accounts, and enumerates returned fields, which clarifies what the call does beyond the 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?

Two short sentences convey scope, exclusions, and optional filtering. Every clause earns its place and the most important verb-resource pairing is front-loaded.

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 a 100%-covered optional parameter sna an output schema plus annotations, the description provides enough scope detail (investment/crypto accounts, no bank holdings) for safe selection and invocation. Slightly more on when to prefer siblings would close the gap, but nothing essential 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?

The only parameter, account_id, has a complete schema description, and schema coverage is 100%. The description merely restates 'Optionally restrict to one account', adding little beyond the schema.

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?

Description opens with a specific verb ('List') and a precise resource: positions held in brokerage and crypto-exchange accounts, not just generic 'holdings'. It lists the returned fields and explicitly notes 'Bank accounts have no holdings', which helps distinguish it from siblings like list_accounts and get_account_balance.

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 description tells the agent when this tool applies (investment/crypto positions) and rules out bank accounts alerting, and the schema points to account_id from list_accounts. It does not explicitly name alternatives or exclusions, but the context is clear enough to select this over list_accounts or get_account_balance.

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