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

Annotations already carry the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, yet the description still adds real value: every result carries a join link, and member counts are only present when organisers stated them, with null meaning unknown rather than small. That null-semantics caveat is exactly the kind of data-interpretation context an agent cannot get from structured fields. It stops short of describing pagination or result-shape beyond those two points.

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?

Front-loaded with the definition, then usage, then the negative case, then the data caveat — a logical order with no filler sentences. The em-dash parenthetical defining communities is slightly verbose but earns its place by preventing conflated records.

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?

There is no output schema, so the description compensates by noting the join link and the member-count null convention, which is the key return-value interpretation an agent needs. Combined with full schema coverage and clear sibling routing, nothing material is missing for a six-parameter, zero-required search 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?

Schema description coverage is 100%, so the schema already documents all six parameters including the platform enum and region formatting. The description restates the filterable axes (free text, region, topic, platform) but adds no syntax or matching-behavior detail beyond what the schema provides, so the 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 ('Search builder communities') and immediately grounds the resource by enumerating what a community actually is (Slack workspaces, WhatsApp groups, meetups). It explicitly separates itself from the sibling search_products by asserting 'Communities and products are separate records'.

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 explicit positive triggers ('when someone wants to reach a scene rather than a person') with concrete examples, and an explicit negative ('Do not call it to find products or their builders — that is search_products'), naming the alternative. Routing is unambiguous.

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