Look up one Firebase Auth account by UID, email, or phone number to inspect user identity details in Firenook emulator workflows.
Look up one Auth account by uid, email or phone number (accounts:lookup).
| Name | Required | Description | Default |
|---|---|---|---|
| uid | No | Account id (localId) | |
| No | Email address | ||
| phoneNumber | No | Phone number in E.164 form |
Changes observed during successful MCP inspections.
v0.2.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are supplied, so the description carries the full disclosure burden, and it adds almost nothing behavioral: it does not say the call is read-only, what happens when no account matches, or whether an error vs. empty result is returned. It also leaves unstated whether one, two, or all three of uid/email/phoneNumber may be supplied at once, which is the main ambiguity for a zero-required-parameter lookup.
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?
A single front-loaded sentence naming the verb, resource, cardinality, and selector set, with no filler. The trailing API operation name is useful for agents matching on backend endpoints.
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 tool with no annotations, no output schema, and zero required parameters, the description should at minimum state that at least one identifier is needed, whether identifiers combine or take precedence, and what is returned (a profile vs. a not-found result). None of that is covered, leaving an agent likely to call it with an empty argument object.
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 each of the three parameters clearly, making 3 the baseline. The description enumerates the same three selectors but adds no precedence rule for the case where multiple identifiers are provided, so it contributes little meaning beyond the schema.
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?
States a specific verb ('Look up') and resource ('one Auth account') plus the three accepted selectors, and the parenthetical '(accounts:lookup)' names the underlying Identity Toolkit operation. It implicitly contrasts with the listing sibling, but never names auth_list_users, so differentiation is left to inference.
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?
'Look up one Auth account' implies single-account retrieval as opposed to the bulk listing done by auth_list_users, but no explicit when-to-use/when-not guidance is given. An agent must guess between this and the many other auth_* siblings (mint_token, set_claims, etc.) from names alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.