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

The description discloses the core side effect (creates an invoice), the return value (hosted payment URL), and an important behavioral constraint (payment methods come from the merchant dashboard, not from parameters). This adds meaningful context beyond the annotations, which only indicate readOnly, idempotent, and destructive hints are all false.

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?

The description is two sentences with no filler. The primary action and return value are front-loaded, and the payment-method caveat is included compactly.

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 create operation with a 100%-covered schema, an output schema, and non-destructive annotations, the description and schema together give an agent everything needed to invoke the tool correctly. The key operational fact—that payment methods come from the merchant dashboard—is explicitly stated.

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 the schema already documents every parameter, including the minimum amount and field purposes. The description adds no new parameter-level meaning beyond stating that the invoice is in USD and that payment methods are dashboard-controlled.

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 states a specific verb and resource: 'Create a FinCobra Checkout invoice in USD' and clearly names the return value ('hosted payment URL'). This distinguishes it from sibling tools like get_invoice and list_sources, which are retrieval operations.

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 clearly implies this tool is for creating checkout invoices and explains that payment methods are controlled by the merchant dashboard rather than caller input. It does not explicitly say 'use this instead of get_invoice', but the creation-versus-read distinction makes the intended use clear.

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

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds behavioral value by specifying the returned data (status, URL, amounts), which is not expressed in the annotations. No contradictions or undisclosed side effects are present.

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?

The description is a single sentence that front-loads the core action ('Look up'), specifies the resource, and lists the key outputs. Every word earns its place, with no redundancy or filler.

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?

This is a simple single-parameter read operation, the annotations fully cover its side-effect profile, an output schema exists to describe return values, and the description states the essential return fields. Nothing material is missing for an agent to select and invoke the tool correctly.

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% — the only parameter, invoiceId, is already documented with 'Invoice id returned by create_invoice.' The description adds no additional parameter meaning beyond saying lookup is by id, so the baseline of 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?

The description uses a specific verb ('Look up') and a specific resource ('a known FinCobra Checkout invoice by id'), clearly distinguishing it from sibling tools like create_invoice or list_sources. It also states the key return contents (status, hosted payment URL, amounts), leaving no ambiguity about the tool's function.

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 phrase 'a known invoice by id' makes it clear this tool is for retrieving an existing invoice, not for creating or listing. It implies the invoice id comes from a prior create_invoice call, which sets context. However, it does not explicitly name alternatives or exclusion conditions, so it stops short of full guidance.

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

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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds valuable context beyond those annotations by revealing that banks, cash, and property are manual entries and that live crypto USD balances are null on the list API. This prepares the agent for null values and the nature of the underlying data.

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?

The description is two sentences with no filler. The first sentence front-loads the core purpose and data source, and the second provides essential caveats about manual entries and null crypto balances. Every sentence contributes useful 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?

With no parameters, a read-only annotation set, and an output schema present, the description is complete for practical use. It explains the two most important behavioral caveats — manual entries and null crypto values — that an agent would need to interpret results correctly.

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?

There are zero parameters, so the schema already fully covers input semantics. The description is not required to add parameter details, and it doesn't attempt to invent any — the baseline of 4 applies.

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 states a specific verb ('Read') and resource ('Watchlist net worth'), and clarifies that it aggregates from existing list APIs. This makes the tool's purpose immediately distinguishable from invoice and source siblings like get_invoice and list_sources.

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 this is the tool to call when the agent needs a watchlist net worth figure, and it gives caveats about manual entries and crypto nulls. However, it does not explicitly state when to prefer this over alternatives such as list_sources, nor does it state when not to use it.

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

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

The annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds little behavioral context beyond the id provenance, and it does not contradict the 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?

One clean sentence with no filler or repeated schema content. The key constraint, that the id comes from list_sources, is front-loaded and immediately actionable.

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?

With a single required parameter, full schema coverage, comprehensive annotations, and an output schema present, nothing essential for calling this tool correctly is missing. The description is fully adequate for the tool's low complexity.

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?

The input schema fully documents sourceId at 100% coverage, including examples like wallet:12, exchange:binance, and manual:3. The description merely restates the provenance relationship already present in the schema, so the baseline of 3 applies.

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 says 'Look up one Watchlist source by the id returned from list_sources.' This uses a specific verb, names the resource, and clearly indicates singular lookup behavior, distinguishing it from list_sources without needing to inspect 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?

It explicitly states that the id comes from list_sources, establishing a clear call sequence for the agent. It does not explicitly enumerate exclusions or alternatives, but the 'one ... by id' phrasing sufficiently implies the contrast with listing.

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

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds useful behavioral nuance: the response conditionally includes stored token PnL cost-basis rows when the API has them, and the operation never mutates data. This complements the annotations without contradicting them.

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 crisp sentences lead with the primary action, then add a conditional inclusion detail, then close with a scope boundary. There is no filler and every sentence contributes information an agent needs to invoke the tool correctly.

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 zero-parameter, read-only listing tool with an output schema available, the description covers what is listed, the conditional PnL inclusion, and the non-mutating nature. Nothing essential is missing for an agent to decide on and execute this tool correctly.

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?

The tool accepts no parameters, so the input schema is already complete. Per the baseline for zero-parameter tools, there is nothing further the description needs to compensate for, and it introduces no parameter-related ambiguity.

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 uses a specific verb ('List') and a defined resource ('Watchlist wallets, exchanges, and manual bank/cash/property sources'), which immediately clarifies what is returned. The boundary clause 'Does not add wallets or edit assets' distinguishes the tool from mutation-focused siblings like create_invoice. This makes the tool's scope unmistakable.

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 clearly establishes when to use the tool: to retrieve a read-only list of watchlist sources, including PnL cost-basis rows when available. It also states a when-not boundary: it does not add wallets or edit assets. However, it never names sibling alternatives such as get_source for a single source, so it stops short of full 5 guidance.

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