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

Annotations already declare the safety profile (write, non-idempotent, non-destructive, open-world). The description adds real behavioral content beyond that: the value must be pre-converted to the topic's unit, and the call reports today's total. No auth, rate-limit, or failure behavior is disclosed, but the added context is material.

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, front-loaded sentences with no filler - the core action leads, followed by the two most error-prone guidance points and the prerequisite. Every sentence earns its place.

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-parameter write tool with a full output schema, the description covers the essential gotchas (unit conversion, backdating, topic id prerequisite). Remaining detail on note/tags/values lives in the schema, so nothing critical is missing, though how to find a topic's unit could be spelled out.

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 schema already documents value conversion ('2 litres is 2000 for a ml topic'), occurredAt semantics, and the required note field. The description's conversion and occurredAt sentences largely restate schema content, adding workflow framing but little new meaning. Baseline 3 applies.

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 - 'Records one entry on a topic' - and the singular 'one entry' implicitly separates it from the batch sibling log_entries. However, it never names that sibling, so the differentiation must be inferred from the plural tool name rather than stated.

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 concrete operational context: call list_topics first if the topic id is unknown, use occurredAt for backdated entries, and convert values before logging. It stops short of naming alternatives (e.g. log_entries for multiple entries, update_entry for corrections).

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