Mailbox MCP

Flag emails

flag_email

Idempotent

Flag messages - the same star/flag marker Outlook and webmail show, and the state search_emails's flagged filter finds. Purely a marker for the user's own attention; it does not move, read, or otherwise change the messages, and it does not mark anything read. Pass the whole set in ONE call. Verified rather than assumed: the flags are read back off the server, so a message that could not be changed is named individually instead of being folded into a success. A uid only means something in the folder it came from, so pass mailbox when the uids did not come from INBOX. Flagging a message that is already flagged changes nothing and is not an error. unflag_email clears it, and is the more dangerous half of the pair.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`uids`	Yes	The UIDs to act on, from list_emails or search_emails. Pass EVERY message you want changed in ONE call - this tool acts on the whole set in a single operation, and doing it that way costs the user one call instead of one per message. Up to 500 at a time. A single message is simply a one-element array.
`mailbox`	No	IMAP folder name. Defaults to INBOX.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

First observedSep 5, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Annotations only encode readOnly=false, openWorld=true, idempotent=true, destructive=false. The description goes further by disclosing the verification behavior (flags are read back and per-message failures are named), the folder-scoped meaning of uids, idempotency behavior for already-flagged messages, and the lack of read/move/delete side effects. It also flags unflag_email as the more dangerous counterpart, making the safety profile clearer.

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

Conciseness5/5

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

The description is longer than average but every sentence carries a distinct purpose: definition, safety scope, batch usage, verification/failure reporting, uid scoping, idempotency, and sibling comparison. It is front-loaded with the core meaning and uses punctuation to keep related concepts tightly grouped.

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?

Given only two parameters, no output schema, and the mutating-but-idempotent behavior, the description covers the essential contexts an agent needs: what the flag represents, what side effects do not occur, how batch calls should be made, how to scope uids to folders, how failures are surfaced, and how it relates to unflag_email. Nothing material is left for the agent to guess.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3. The description adds real value beyond the schema by explaining that uids are only meaningful in the folder they came from and that mailbox must be supplied when they did not originate from INBOX. The 'pass the whole set in ONE call' guidance reinforces the uids schema, though some of it repeats the schema's own description.

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?

Description opens with a specific verb and object ('Flag messages') and defines the exact semantic: a star/flag marker matching Outlook/webmail and the state search_emails's flagged filter reads. It also distances itself from sibling operations by saying it does not move, read, or otherwise change messages, so an agent can reliably distinguish it from mark_read, archive_email, move_email, and delete_email.

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

Usage Guidelines5/5

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

Gives explicit operational guidance: pass the whole set in one call, supply mailbox when uids did not come from INBOX, and expect no error when flagging an already-flagged message. It names the direct alternative unflag_email for clearing, and clarifies that this tool does not mark anything read, steering selection away from mark_read-like use cases.

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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TDQS

A4.3/5.0

Disambiguation4/5

Most tools target clearly distinct actions and resource types, and the near-overlapping pairs (archive_email vs move_email, check_bounces vs check_receipts) are explicitly cross-referenced in their descriptions. However, the delivery-status pair genuinely overlaps — both scan inbound mail to answer "did my message get there?" — and archive_email is functionally a role-aware move_email, so an agent could still select the wrong one without careful reading.

Naming Consistency4/5

Virtually every tool follows a consistent verb_noun pattern with clear prefix families (check_*, create_*, draft_*, list_*, mark_*, read_*). The single outlier is not_junk, which breaks the mark_* symmetry of its counterpart mark_junk and is not a standard verb-noun construction, though it remains perfectly readable.

Tool Count3/5

31 tools is firmly in the heavy range, though email is a genuinely broad domain spanning send/reply/forward, three draft variants, folder management, flags, junk handling, and diagnostics. Real consolidation was possible — check_bounces and check_receipts could be one delivery-status tool, archive_email is a special case of move_email, and the read-state/flag pairs could take boolean parameters — but each tool has a defensible job.

Completeness4/5

The core email lifecycle is thoroughly covered: send/reply/forward, three draft types plus draft editing, read/search/list/thread, full folder CRUD, move/archive/delete, flags, read state, junk handling, and file-upload intake. Minor gaps exist — there is no permanent-deletion or purge tool, no filter/rules management, and identity/contact maintenance is deliberately out of scope — but real user workflows can be completed without dead ends.

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