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

With no annotations, the description carries the full burden and does so: it declares the read scope (CompanyMember read), defines the status lifecycle and which states accept vs refuse postings, states that a posting into a closed period fails, and points to the reopen flow including 'reason required'. This is unusually complete behavioral disclosure for a list 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?

Purpose is front-loaded in the first line, and each subsequent paragraph adds real value (status semantics, filter behavior, sibling exclusion). It is dense and slightly long, with incidental parentheticals (ZET-161), but almost nothing is 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?

For a two-parameter list tool with no output schema and no annotations, the description is nearly self-sufficient — it even names the fields each row carries. The remaining gap is the absence of explicit company_id semantics and any note on result size/ordering.

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 0%, so the description must compensate. It fully explains fiscal_year_id ('narrows to one year; omitted, every year's periods come back') but gives no explicit semantics for the required company_id beyond the permission note. One of two parameters is meaningfully covered.

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 ('The company's accounting periods — the months a journal entry may post into') and explicitly distinguishes itself from the sibling list_gl_vat_periods. An agent can tell instantly what it returns and what it does not.

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?

Gives explicit when-to-use ('find the period_id a manual journal entry needs, and to check why a posting date was refused') and a concrete when-not/alternative ('This is not the VAT filing calendar — those are the gl_vat_period rows of GET …/gl/vat/periods'). Routing is fully determined.

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