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

The annotation already declares destructiveHint=true, so the mutation nature is covered structurally. The description adds real behavioral context beyond that: the expense may be tied to a vendor/client/project and can be flagged for re-invoicing, plus the underlying endpoint. It still omits permissions, reversibility, or confirmation behavior, so it 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?

Two tight sentences with the core purpose front-loaded and no filler. The trailing endpoint reference ('POST /api/v1/expenses') is slightly meta but useful for API mapping, keeping it just short of maximally efficient.

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 14-parameter mutation with only one required field and no output schema, the description is thin: it never surfaces the required amount, gives no sense of the returned record, and says nothing about side effects. It covers purpose and some optional associations but leaves an agent under-informed about the write.

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 79%, just under the high threshold, and the schema already documents most parameters (date, amount, client_id, vendor_id, project_id, currency_id, etc.). The description's mention of vendor/client/project ties loosely mirrors existing param docs but adds no syntax or format detail, and the undocumented fields (tax_name1, tax_rate1, private_notes) remain unexplained.

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 ('Log an expense') and enumerates the optional associations (vendor, client, project) plus the re-invoicing flag, which goes beyond a bare restatement of the name. It does not, however, distinguish itself from the many sibling create_* tools, so an agent must infer that this one is the expense-specific creator.

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?

There is no when-to-use or when-not-to-use guidance and no routing to alternatives such as list_expenses or the invoice-creation tools. The description only implies usage through the optional associations; it never tells the agent when this tool is the right choice.

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