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

Goes well beyond the annotations (readOnlyHint=false, idempotentHint=true, openWorldHint=true) by disclosing the required scope registre:write, that idempotency_key is sent as the Idempotency-Key header with 24 h retention and replay semantics, fail-closed behavior for non-Québec cadastres, and that the caller must supply their own Bearer API key. Billing behavior per document, per test key and per 4xx/5xx is also spelled out.

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-loads the route and purpose, which is good, but the body is roughly doubled in length by full English/French duplication and by three separate billing sentences that restate the same fee logic. The useful content is there, but it is not tight.

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 billable write-scoped external call with no output schema, the description covers auth, scope, idempotency, edge-case failure mode and the full cost model, including the Registre's separate 1,50 $ charge. An agent has everything needed to invoke it correctly and predict the consequences.

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 already 100%, so the baseline is 3; the description earns an extra point by adding real semantics for idempotency_key (header transport, 24 h store, retry returns the stored answer) and by explaining that cadastre non-default values fail closed.

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 concrete verb+resource (retrieve the cadastral plan of one lot in the Cadastre du Québec) and names the underlying route POST /v1/plans. An agent can tell it apart from acte_get or lot_get by the document type. It stops short of explicitly contrasting itself with those siblings, which keeps it at 4 rather than 5.

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 context is only implied: 'A stored plan has no Registre fee; other cadastres fail closed' tells the agent a constraint but not when to prefer this tool over acte_get, lot_get, or registre_index_request. No explicit when-not or alternative routing is given.

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