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

With no annotations, the description carries the full burden and does well: it discloses that this writes to the caller's own ledger, requires a bearer API key, and consumes the same monthly allowance as the REST endpoint (a quota constraint). It stops short of stating idempotency, duplicate handling, or failure behavior for a mutation tool.

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 sentences, front-loaded with the action and resource, then the side effects and auth/quota conditions. No filler; every clause carries information.

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 six-required-parameter mutation with no annotations and no output schema, the description covers auth, ledger target, and quota side effects well. It leaves open what the call returns (e.g., updated monthly total) and how duplicate or invalid trips are handled.

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% with enums for mode and paid_with, so the schema documents all six parameters including examples for from/to. The description's parenthetical field list merely restates what the schema already provides, adding no new syntax or format detail.

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 ('Record one public transport trip') and enumerates the payload fields it captures. The clause about counting toward a monthly total and subsidy estimate ties it to what the sibling read tools (monthly_summary, subsidy_amount) report, so the agent can place it in the workflow.

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?

Makes the write-vs-read split clear by describing this as the recording action that feeds the monthly total, implicitly contrasting with the sibling summary/fare tools. It does not explicitly say when NOT to use it (e.g., duplicate-trip handling) or name alternatives for correction/update scenarios.

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