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

With no annotations, the description carries the full burden of behavioral disclosure. It explicitly states the output fields and filtering capabilities, implying a read-only query operation. It does not mention edge cases like empty results or ordering, but for a search tool this is sufficient.

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?

The description is three concise sentences: purpose, output fields, and filter options. It is front-loaded with the main action, has no redundant information, and every sentence adds value.

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 tool with 4 parameters, 1 required, no output schema, and no annotations, the description provides enough context: it names return fields, filter capabilities, and the resource type. It does not specify sorting or defaults, but the schema covers defaults. Overall, it is complete for an agent to select and invoke the tool.

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?

The input schema has 100% coverage with descriptive parameter explanations. The description's mention of filtering by level, minimum spots, or time window mirrors the schema without adding new semantics. No additional parameter relationships or formats are disclosed, so the baseline score of 3 is appropriate.

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?

The description clearly states the tool finds available surf sessions at a pool, with a specific verb and resource. It also lists returned data (date, time, skill level, available spots, booking URL) and distinguishes itself from sibling tools (get_session_levels, list_pools) by focusing on session availability.

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?

The description provides clear context for when to use the tool (finding sessions) and mentions filter options (level, minimum spots, time window). However, it does not explicitly mention alternatives or when not to use it, such as pointing to get_session_levels for level names or list_pools for pool IDs.

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