get_entity_invoice_explainer

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

Annotations clearly indicate readOnlyHint=true and destructiveHint=false, so the agent knows it's safe. The description adds that it explains changes and returns cost changes, which is some behavior. But it doesn't disclose details like whether it handles multiple currency adjustments, pagination, or formatting, though with readOnlyHint, a mid-score is reasonable.

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?

Two sentences, clear and to the point. It front-loads the core purpose and scope. No wasted words, but could perhaps be more structured with a line break, still fine.

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 the tool is moderate complexity (4 params, no output schema, some annotations), the description provides basic purpose and scope. It doesn't explain the return format (what 'returns invoiced cost changes' means in detail) or how to handle customerContext for different user types, which is partially described in schema. For a read-only analysis tool, it's adequate but not comprehensive.

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 25%: only customerContext has a description. The description itself does not explain what billingProfileId or invoiceNumber mean or how they relate to the invoice. While invoiceNumber pattern is in schema, the description provides no extra semantics. It fails to compensate for the low schema coverage, leaving two required params underdocumented.

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 clearly states the tool explains month-over-month changes in invoiced cloud costs, with a specific scope (invoice owned by billing profile in authenticated tenant). It distinguishes from siblings like list_invoices and get_invoice which handle listing/retrieval, not explanatory analysis.

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 description implies usage: when you need to explain month-over-month cost changes for an invoice. It doesn't explicitly state when not to use it or compare to similar tools like get_billing_explainer_per_payer. The sibling get_billing_explainer_per_payer might be an alternative, but no comparison is given, leaving some ambiguity.

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