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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false, so the safety profile is known. The description adds real value beyond that by disclosing the external side effect ('Aryeo may email the new customer an invitation') and the underlying endpoint, which an agent cannot infer from annotations.

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: purpose and required inputs first, dedupe guidance second, side effect third, endpoint last. No filler and every sentence carries information.

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?

Given a create tool with full schema coverage and annotations covering mutability, the description covers what is needed to invoke it correctly, including the duplicate-check workflow. The one gap is that it says nothing about what comes back (e.g., a new customer ID), which matters for follow-up calls when no output schema exists.

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 every one of the 10 parameters is already documented in the schema. The description only reaffirms the three required fields (owner name, email) and adds nothing about optional fields like timezone, phone, or team_name. Baseline 3 is appropriate.

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?

Names a specific verb and resource ('Create a customer') and even defines the domain object ('an agent or brokerage that can place orders'), plus the minimum inputs. This is clearly distinguishable from siblings like aryeo_list_customers or aryeo_update_order_notes.

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 an explicit precondition and names the alternative: 'Look the email up with aryeo_list_customers first to avoid duplicates.' That is actionable routing guidance, though it does not state when not to use this tool or what to do if a duplicate is found.

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