get_portfolio_breakdown

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

Annotations already provide readOnlyHint=true, so the description adds value by disclosing gating (Premium-gated) and authentication requirement (IWMM_API_KEY). It does not describe output format details beyond 'each with value, count, and share' or mention rate limits, data freshness, or side effects. This is adequate but not rich.

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?

The description is concise at two sentences, front-loading purpose and output format, then adding gating info and a sibling reference. Every sentence provides value with no fluff.

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?

Given the tool's complexity (enum with special cases, no output schema), the description covers core purpose, output structure partially, and references a key sibling. It omits details like overall summary alternative (get_portfolio_summary) but is sufficient for a read-only breakdown tool with well-documented parameters.

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 descriptions for both parameters, including enum values and special behavior for 'cost-basis' and 'color'. The description does not add significant meaning beyond what the schema provides, so baseline 3 is appropriate.

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?

The description clearly states the tool's function: 'Get the user's collection value broken down by a dimension into slices (each with value, count, and share).' It uses a specific verb ('Get') and resource ('collection value broken down'), and distinguishes from sibling 'get_portfolio_breakdown_cards' by noting it's for drilling into one slice.

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 provides usage context by noting it is 'Premium-gated' and 'Requires IWMM_API_KEY', and gives an explicit alternative: 'Use get_portfolio_breakdown_cards to drill into one slice.' However, it does not compare with other siblings like get_portfolio_summary or explicitly state when not to use this tool.

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