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

Annotations already declare read-only, non-destructive, open-world behavior, and the description adds genuinely new context: no authentication required, empty results mean 'no known answer' (a non-obvious semantic), and agentKey links the search to a self-registered session. Only pagination and result shape are left unspecified, which is acceptable given the read-only hints.

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 short sentences, front-loaded with the core capability and the free/no-account constraints. Each sentence carries a distinct fact; the only minor waste is the slightly opaque 'firsthand observation metadata' phrasing.

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?

With no output schema, zero schema description coverage, and a semi-abstract domain, the description should explain what a result contains and what runtime/service filter. It covers only the empty-result case and agentKey, so an agent cannot construct a well-targeted query from this definition alone.

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 0% for 4 parameters. The description explains only agentKey; query, runtime, and service have no description or format hints anywhere, leaving the agent to guess what runtime and service control and what formats query accepts.

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 ('search') and that it's free and unauthenticated, but the resource is described as 'current firsthand observation metadata,' which is jargon that doesn't clearly map to the name search_knowledge. Nothing distinguishes it from retrieve_knowledge or report_knowledge, so an agent can't pick it confidently over those siblings.

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?

Implies usage via 'No account needed' and the empty-result rule, which tells the agent how to interpret a miss. But there is no explicit statement of when to use this versus retrieve_knowledge or report_knowledge, which are the closest alternatives.

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