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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent write. The description adds genuinely new behavior: the cap table is linked to an existing company valuation, and an existing cap table may be returned rather than a new one created. That last point is in mild tension with idempotentHint=false but is not a flat contradiction, since the short-circuit depends on prior state rather than on repeat-call semantics.

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 action and followed by the linking behavior and the usage restriction. Nothing is padded, though the parenthetical could be folded more tightly into the second sentence.

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 two-parameter create tool with full annotation coverage and no output schema, this covers the essentials: what is created, what it links to, and when not to call it. It does not describe required permissions or what the returned object looks like, which would be the remaining 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?

Schema description coverage is 100%, so the schema already explains both the company name and the 3-letter currency code. The description adds no parameter-level syntax, defaults, or validation beyond that, so 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 ("Creates a cap table for a company") and adds a linking nuance to an existing Equitest valuation. It is clear what the tool does and implicitly distinct from read-side siblings like get_cap_table and list_cap_tables, though those are never named.

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 sentence "Use only when the user asks to create one" gives an explicit exclusion, which is a real guardrail against speculative creation. However, it names no alternatives, so an agent must infer from sibling names that viewing or listing existing cap tables belongs to get_cap_table or list_cap_tables rather than here.

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