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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds some genuine behavioral context beyond them — the 13F lag ('change from the previous quarter', 'Form 4 purchases since the 13F') and the fact that overseas values are estimated rather than reported — but says nothing about cost/latency of this composite call, invalid-slug behavior, or how limit interacts with the result set.

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?

A single front-loaded sentence that leads with the broad claim and then itemizes sources, with no filler or restatement of the name. It is dense to the point of being a run-on list, but every clause names a distinct data source rather than padding.

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 must describe what comes back, and it does so thoroughly by naming each source family (13F, overseas regulator filings, N-PORT, 5% stakes, Form 4, filing cadence). The remaining gaps — result shape, ordering, truncation under limit — are modest for a read-only lookup whose annotations already convey safety.

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%, including the slug example and the limit default/max, so the schema does the heavy lifting. The description adds no parameter-level meaning at all — it never mentions slug or limit — which is acceptable at full coverage but earns only the baseline.

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 opening clause ('Everything moatshark has on one value investor') plus the enumerated content makes clear this is a comprehensive per-manager holdings retrieval, distinguishable from get_company and the filing-oriented siblings by scope. It never explicitly contrasts itself with search or insider_buying, so the sibling differentiation is inferred from the data inventory rather than stated.

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?

Usage is only implied: an agent can infer 'use this when you want the full picture on a known manager,' but there is no explicit when-to-use, when-not-to-use, or pointer to alternatives such as search (to find the slug) or insider_buying for a narrower view. The schema's 'slug from search' note carries the only workflow hint.

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