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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the safety profile is covered. The description adds that liquidation terms are attached to the new class and reiterates the seniority ordering, but says nothing about what happens if the class already exists (despite non-idempotency), whether the cap table is auto-created, or whether the operation is reversible.

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 example, then the seniority rule, then the usage guardrail — no filler. The seniority sentence is arguably redundant with the schema, but the overall structure is tight and scannable.

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?

This is a 10-parameter mutation with no output schema and thin schema coverage, and the description does not close the gap. An agent still lacks guidance on defaulting kind/participating/conversion_ratio, on cap_table resolution (which the schema covers), and on the result of the call, so the definition is under-specified for the tool's complexity.

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 only 30% across 10 parameters, so the description must compensate — and it largely does not. It adds meaning only for name (example format) and seniority (which the schema already documents verbatim as "Higher is paid first"), leaving kind, participating, conversion_ratio, authorized_shares, liq_pref_multiple, participation_cap, and original_issue_price unexplained in either place.

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 verb and resource ("Adds a share class") and grounds it with a concrete example ("Series A Preferred") plus the scope note that liquidation terms come with it. It is clearly distinct from read-side siblings like get_cap_table and list_cap_tables, though it never explicitly contrasts with adjacent write tools such as create_cap_table or simulate_funding_round.

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?

"Use only when the user asks" supplies a real gating condition — do not add share classes proactively — which is more than most mutation tools offer. However, no alternatives are named (e.g., when to use simulate_funding_round instead), no prerequisites such as needing an existing cap table are stated, and the phrase is ambiguous about whether it forbids any inference of intent.

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