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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, so safety is covered structurally. The description goes beyond that by disclosing the chart-of-accounts seeding side effect and concrete validation constraints on the first fiscal year (max 18 months, end must be the last day of the end month, omission yields nearest year-end), which is genuinely useful behavioral context.

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?

Front-loaded with purpose and side effect, then the argument list; every clause carries information (enums, month mapping, date rules) rather than filler. The single long argument sentence is dense but not padded.

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 9-parameter creation tool with no output schema and thin structured coverage, the description covers purpose, side effect, parameter meaning and key constraints. It omits behavior on duplicate orgnr, error conditions, and what the caller gets back, which are minor given the tool's scope.

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 11%, so the description must compensate and largely does: it enumerates vat_period values (manad|kvartal|ar), accounting_method values (faktura|kontant), decodes fiscal_year_end_month numerically (12=jan-dec, 11=dec-nov), and explains first_fy_start/first_fy_end with an example and constraints. It leaves name, city and fiscal_year itself unexplained, so it stops short of full compensation.

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 ('Lägg till ett bolag i koncernen') and immediately discloses a consequential side effect ('seedar BAS-kontoplanen') and the scope ('Scope book'). An agent can distinguish this from get_company, update_company, search_company and list_companies without opening the schema.

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 purpose makes the usage context inferable (onboard a new group company), but there is no explicit when-to-use/when-not statement, no mention of prerequisites, and no pointer to alternatives such as update_company for later edits. Usage is implied rather than guided.

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