fermi

Check account and quota

whoami

Read-onlyIdempotent

Cost: free. Checking never spends quota or credits, and never consumes an anonymous estimate.

Report who you are to Fermi, what a call will cost, and what is left.

Call this BEFORE an `estimate` if you need to know whether it will spend
the free anonymous allowance or an account's credits, or AFTER one to see
the new balance. It works anonymously, it is free, and it consumes
nothing -- including the anonymous daily allowance it reports.

Args:
    api_key: Your Fermi API key from POST /api/v1/accounts. Omit to ask
        about the anonymous caller this transport resolves to. On the
        Streamable-HTTP transport an `Authorization: Bearer fmi_pat_...`
        header authenticates this call too, with no argument needed.

Returns:
    billing: the same block every other Fermi tool response carries --
        principal ("anonymous" or "account"), account_id,
        account_status, auth_source ("bearer", "api_key" or
        "anonymous"), charged_to, credits_charged, credit_balance,
        is_unlimited, anonymous_estimates_remaining_today, and
        anonymous_quota_resets_at.
    tiers: each tier's credit_cost, delivery mode ("sync"/"async") and
        whether it supports the anonymous trial.
    price_per_credit_usd: what one credit costs to buy.
    recent_transactions: the account's last 10 credit-ledger entries;
        null for an anonymous caller, which has no ledger.

Input Schema

Name	Required	Description	Default
`api_key`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

AddedOct 28, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Beyond the read-only and idempotent annotations, the description adds important behavioral context: the call is free, spends no quota or credits, does not consume the anonymous daily allowance it reports, and works anonymously. It also explains bearer-header authentication behavior for the HTTP transport.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured and front-loads the critical cost/free behavior before usage and argument details. It is somewhat verbose, repeating the free/no-consumption point and enumerating return fields even though an output schema already exists.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a one-parameter, read-only account-check tool, the description covers the identity, cost, quota, anonymous-vs-account behavior, and authentication details an agent needs. Since an output schema exists, the additional return-value explanation is not required, but the definition is otherwise complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Although schema description coverage is 0%, the description fully explains the single `api_key` parameter: where to get it, that omitting it targets the anonymous caller, and that a bearer header can authenticate without passing it. This compensates for the schema's lack of parameter documentation.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific purpose: report the caller's identity, call cost, and remaining quota. This clearly distinguishes whoami from estimate and other sibling tools by focusing on account/quota state rather than producing a cost estimate.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives explicit before/after guidance relative to `estimate`: call before to see whether an estimate will spend anonymous allowance or credits, and after to see the new balance. It does not explicitly cover when not to use it or mention other siblings such as `get_estimate`, but the primary usage context is clear.

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

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