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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent, closed-world write, so the safety profile is covered. The description adds genuinely new behavioral context: the write requires OAuth sign-in with the crosodo:write scope, only one expense is created per call, and values are taken verbatim as the baker's own numbers rather than converted or validated. It does not say what the response contains or whether duplicate entries are rejected.

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?

Four short sentences, front-loaded with the action and destination, then prerequisites. The Cottage Pro clause is compact but somewhat cryptic without dashboard context; otherwise there is little waste.

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 5-parameter write tool with full schema coverage and no output schema, the description covers purpose, authentication, cardinality, and a domain rule about Cottage Pro eligibility. Only the post-write result behavior (what is returned, how the entry appears on the Financials tab) is left unexplained.

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?

With 100% schema description coverage (including the category value list and YYYY-MM-DD date format), the schema does the heavy lifting, so 3 is the baseline. The description only adds the note that amounts are the baker's own numbers, which clarifies amountUsd semantics slightly but adds nothing about category, vendor, or note.

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?

"Add one expense to the signed-in baker's Financials tab" gives a specific verb (add), resource (expense), cardinality (one), and destination (Financials tab). It implicitly separates itself from log_sale and get_my_dashboard via the expense/revenue distinction, though it never names a sibling explicitly.

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?

Usage is implied rather than stated: an agent can infer this is the tool for recording a single expense entry, and the OAuth requirement is a useful precondition. There is no explicit when-not guidance or pointer to alternatives (e.g., log_sale for revenue, get_my_dashboard for reading totals).

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