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

Annotations only cover safety (readOnlyHint, openWorldHint). The description adds substantive behavior the annotations cannot: newest-first ordering, the literal strict-AND keyword matching semantics, and the important caveat that topSnippet shows the document opening rather than the match location.

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?

Three dense sentences, front-loaded with purpose then usage then caveats; every clause carries distinct information (when-to-use, filter semantics, snippet caveat, date pairing) with no filler.

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 read-only list tool with an output schema present, the description need not explain return values, and it still volunteers the one return detail that matters (topSnippet scope). Combined with 80% schema coverage and safety annotations, an agent has everything needed to call it correctly.

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 80%, so the schema already documents most parameters. The description nonetheless adds real meaning: the coupled start/end pairing requirement, the strict-AND literal behavior of keyword (schema only says 'every word must appear'), and the start/end ISO format. It says nothing extra about limit or provenance, so it is not fully complete.

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?

Starts with a specific verb+resource ('List the user's saved Sensefold items'), adds ordering scope ('newest first'), and implicitly demarcates itself from the retrieval siblings by describing it as a browsing/recency tool. An agent can distinguish it from search_hub and get_item without opening schemas.

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?

Explicitly names the use cases ('recency questions', 'date-range browsing') and the exclusion plus alternative ('for topic lookup or locating matches use search_hub instead'). It also states a prerequisite ('Provide start and end together as an ISO date range'), leaving nothing to inference.

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