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

Annotations already declare readOnly, idempotent, closed-world and non-destructive. The description adds two genuinely new facts: authentication is required and result depth is plan-dependent. However, "depth follows the plan" is undefined — it does not say whether results are truncated, capped, or paged, which is exactly what an agent needs to interpret an unexpectedly short list.

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?

Two dense sentences with the core result shape front-loaded, then the optional filter and access constraints. It is efficiently sized, though the em-dash clause crams four return fields together and the plan caveat is vague rather than precise.

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, the description usefully enumerates the returned fields and states the auth requirement, which is the main thing an agent needs before calling. The gaps are the unspecified default limit / result cap and what "depth follows the plan" concretely implies.

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 only 50%: trend is documented in the schema, but limit has no description beyond its 1–50 bounds and no stated default. The description clarifies trend's optional semantics but never mentions limit, so it does not compensate for the undocumented parameter half.

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 states a specific resource and operation: companies ranked by EquiReason's verdict, with the return fields enumerated (band, score, matched trend, evidence count). It is clear what the tool returns, though it never explicitly names how it differs from the sibling search_companies.

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?

"optionally for one trend" plus the schema note that trend is a trend_id from list_trends gives a concrete cross-reference for one path. But there is no guidance on when to prefer this over search_companies, nor any exclusion or prerequisite detail beyond the sign-in note.

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