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

Adds substantial behavior beyond the annotations: idempotency ('safe to repeat and safe after a different starter'), non-destructive merge semantics ('metrics the workspace already has are left as they are'), the empty-start state, and a conditional return ('May return needs_confirmation'). These are exactly the mutation traits an agent needs and are not derivable from the schema or hints.

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?

Front-loaded with the core action and dense with distinct facts (slugs filter, idempotency, empty state, next step, confirmation return). Every sentence earns its place; slightly list-like but no filler.

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 mutation tool with no output schema and 75% param coverage, it covers lifecycle, idempotency, and the confirmation return well. The only real gap is that approvalId (the confirmation path) is not tied to the 'needs_confirmation' mention, leaving that flow slightly under-explained.

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 75% and the schema already documents slugs ('The starter's metrics to keep. Omit for all of them') and starter. The description's 'Pass `slugs` to keep only some' largely restates that. The undocumented approvalId is never explained, so no real value is added over 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?

States a specific verb and resource: 'Creates a starter's metrics at their levels and links them.' This is clearly distinct from ledger_metric_starters_list (read) and readable in the name. However it never explicitly contrasts itself with the closely related ledger_metric_presets_adopt, leaving the starter-vs-preset choice to inference.

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 clear operating context: 'Pass `slugs` to keep only some of its metrics' and 'Adopt only what the user agreed to', plus explicit next steps (connect a source via ledger_feeds_create). It does not state when NOT to use it or name the preset alternative, so it stops short of full routing.

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