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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=true and openWorldHint=false, so the safety profile is covered by structured data. The description adds the write-scope requirement, which the annotations do not. It does not clarify partial-vs-full replacement semantics, whether omitted fields are preserved or cleared, or what happens when the ID does not exist — meaningful gaps for a destructive mutation.

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 tight clauses: the action is front-loaded, the UI anchor follows, and the auth requirement is appended last. No filler sentences and nothing that repeats the title verbatim.

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 single-record mutation with annotations covering the safety profile, no output schema, and fully documented parameters, the description covers purpose, identifier and auth. It stops short of describing update merge semantics and error behavior on an unknown ID, which would matter for a tool with only one required parameter.

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 description coverage is 100% across all 12 parameters, so the schema carries full parameter meaning, including the non-obvious purchase_order_id balance interaction. The description adds nothing beyond the schema about which fields are updatable or how enums/date formats are interpreted. 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?

States a specific verb (Update) and resource (an existing asset cost entry) with the lookup key (by ID), and anchors the resource to the AssetLab 'Expenses' page so the agent can map it to a UI concept. It does not explicitly distinguish itself from update_infrastructure_asset_cost or update_expense, which are the nearest siblings in a very large toolset, so it falls short of a 5.

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 one concrete prerequisite ('Requires asset_costs:write scope'), which is useful authorization context. However it never says when to use this tool versus update_expense or update_infrastructure_asset_cost, nor when an agent should prefer delete_asset_cost plus create_asset_cost instead. Usage is implied by the name only.

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