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

With no annotations, the description carries the full burden. It discloses staleness explicitly ('may be stale') and details the return structure including age_days and stale_warning, which are critical behavioral signals. It does not mention mutations (though 'get' implies read-only) or any access requirements, but the disclosure of staleness and freshness fields is valuable and above baseline for a read tool.

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 concise and well-structured: the first sentence states purpose, the second gives usage guidance, and the third lists return fields. It is front-loaded with the core purpose. The return field list is somewhat verbose but adds value by clarifying output shape. No wasted words, though the return list could be trimmed if an output schema were actually provided (but it's not, so it 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 one-parameter tool with a simple retrieval purpose, the description covers the essentials: what it does, when to prefer alternatives, and the exact shape of the return object. It lacks an explicit definition of 'entity' and does not describe error handling beyond the {found:False} case, but given the tool's simplicity and the presence of an output schema (even if not shown), it is reasonably complete. Missing the entity definition is the main gap.

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 only parameter 'entity' receives no description in the input schema (0% coverage) and the description merely says 'for an entity' without defining what an entity is (e.g., a tech entity, a company, a model). This fails to adequately compensate for the schema's lack of information. The agent would have to infer semantics from sibling tools or external context, which is insufficient for correct invocation, especially given the parameter is required.

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 returns a 'short synthesis brief for an entity' and notes it may be stale. This is a specific verb and resource, and it distinguishes itself from live community/HN tools by explicitly marking itself as potentially stale, which is a functional differentiator from siblings like content_brief or live search tools.

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 explicit guidance on when NOT to use the tool: 'Prefer live community / HN tools for current voice' and 'Model-compare playbooks should not depend on briefs for brand-new models.' This naming of alternatives and exclusion of use cases gives the agent clear routing information, exceeding the typical minimal guidance.

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