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

Goes well beyond the annotations: it states PATCH semantics ('every parameter left out keeps the value the record has now'), discloses the consequence of deactivation ('an inactive account is not offered for new expenses; its expenses stay'), and flags that the default accounts cannot have their name and code changed. IdempotentHint and destructiveHint are already declared, but the preservation guarantees and field restrictions are described only here.

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 verb and resource, and most sentences carry distinct information (scope, active semantics, PATCH rule, permission gate). The opening sentence is a long multi-clause run-on and 'Give only what changes' slightly restates the following clause, costing a little efficiency.

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 7-parameter mutation with no output schema and annotated safety hints, the description covers semantics, permissions and preconditions well. It does not indicate what the call returns or how failures surface, which is the main remaining gap given the absence of an output schema.

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%, so the baseline is 3. The description still adds meaning the schema does not carry: the partial-update contract ('give only what changes'), the fact that omitted fields retain current values, and the constraint on editing name/code for starter accounts.

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 (Changes) plus resource (an expense account) and enumerates exactly which attributes can be modified: name, code, IRD return line, active. It also names the sibling that supplies the id (list_expense_accounts), so an agent can distinguish it from create_expense_account or update_expense without opening a schema.

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 real preconditions – read the record first, confirm the change with the person, and only use it for an organisation where the connection may add and change records (list_organisations identifies which). It stops short of explicitly contrasting with the sibling create_expense_account / update_expense tools, so it is strong context rather than full when/when-not/alternatives routing.

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