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

Annotations already declare readOnlyHint=false, idempotentHint=false, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful pricing context ('Fixed price $0.25 per call') that appears nowhere in structured fields. It loses credit for claiming it turns a 'PDF' into fields while the schema only accepts 'Document text to process' — an agent may try to pass a file path or binary and fail, and no batching, size limits or latency behaviour is disclosed.

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, front-loaded with the extraction scope, then cost, then the user-facing rationale. Every sentence carries information, though the final clause ('without retyping') is marketing framing rather than operational guidance.

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 output schema, the description correctly compensates by enumerating the returned fields, which is the most important completeness requirement here. It still leaves two things unresolved: how this differs from the sibling extractors, and whether the input is raw text or a PDF, a mismatch between description and schema that could cause a failed call.

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 both parameters are documented structurally and the baseline of 3 applies. The description's field list describes output content rather than parameter meaning, and it adds no detail on the optional currency_hint or on the expected format of the document text, so it does not exceed the baseline.

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?

Specific verb ('Extract') plus resource (invoice) and an explicit enumeration of the fields returned (supplier, dates, totals, tax, line items, payment terms), so the agent knows exactly what comes back. It does not, however, distinguish itself from near-identical siblings fikra_extract_invoice and fikra_extract_invoice_fields, which an agent would have no basis to choose between.

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 gives no when-to-use or when-not-to-use guidance, and never names an alternative. With three overlapping invoice-extraction siblings in the catalog, the absence of any routing rule is a real gap; the only hint is the implicit 'PDF or pasted invoice' input framing.

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