diff --git a/src/api.rs b/src/api.rs
index 47c7683..80d6202 100644
--- a/src/api.rs
+++ b/src/api.rs
@@ -24,6 +24,7 @@ pub mod query;
 pub mod routes;
 pub mod state;
 
+/// OpenAPI tag for all endpoints.
 const TAG: &str = "little-librarian";
 
 /// OpenAPI documentation configuration.
diff --git a/src/api/jobs.rs b/src/api/jobs.rs
index ae9bdb5..933fddc 100644
--- a/src/api/jobs.rs
+++ b/src/api/jobs.rs
@@ -8,8 +8,10 @@ use uuid::Uuid;
 use crate::storage;
 use crate::storage::jobs::AddError;
 
+/// Manage background job execution and storage.
 #[derive(Clone, Debug)]
 pub struct JobManager {
+    /// Database connection for job storage.
     db: Arc<storage::jobs::Jobs>,
 }
 
@@ -21,10 +23,12 @@ pub enum ExecuteError {
 }
 
 impl JobManager {
+    /// Create a new job manager with database connection.
     pub fn new(db: Arc<storage::jobs::Jobs>) -> Self {
         Self { db }
     }
 
+    /// Execute a task in the background and return job ID.
     pub async fn execute<F, Fut, T, E>(&self, task: F) -> Result<Uuid, ExecuteError>
     where
         F: FnOnce() -> Fut + Send + 'static,
@@ -49,6 +53,7 @@ impl JobManager {
     }
 }
 
+/// Mark job as successful and store result.
 async fn success<T>(job_id: &Uuid, result: &T, db: &storage::jobs::Jobs)
 where
     T: serde::Serialize + Send + Sync + 'static,
@@ -66,6 +71,7 @@ where
     }
 }
 
+/// Mark job as failed and log error.
 async fn failure<E>(job_id: &Uuid, error: E, db: &storage::jobs::Jobs)
 where
     E: snafu::Error + Send + Sync + 'static,
diff --git a/src/api/query.rs b/src/api/query.rs
index 2661a27..5e6c672 100644
--- a/src/api/query.rs
+++ b/src/api/query.rs
@@ -18,6 +18,7 @@ use crate::{
     storage::{self, queries::DocumentMatch},
 };
 
+/// Maximum allowed limit for query results.
 const MAX_LIMIT: usize = 10;
 
 /// Errors that occur during query processing.
@@ -83,7 +84,7 @@ pub struct QueryStartResponse {
     pub id: String,
 }
 
-/// Execute a semantic search query against the document database.
+/// Execute a semantic search query against the document database and return the job id.
 #[utoipa::path(
     post,
     path = "/query",
@@ -151,6 +152,7 @@ impl HttpStatus for RetrieveError {
 
 http_error!(RetrieveError);
 
+/// Get results for a completed query job.
 #[utoipa::path(
     get,
     path = "/query/{id}",
diff --git a/src/extractors/epub.rs b/src/extractors/epub.rs
index 5e7061a..7235c0c 100644
--- a/src/extractors/epub.rs
+++ b/src/extractors/epub.rs
@@ -6,8 +6,10 @@ use zip::result::ZipError;
 
 use super::extractor::{EpubSnafu, ExtractionError, Extractor, extension};
 
+/// EPUB text extractor.
 pub struct Epub;
 
+/// Errors that occur during EPUB text extraction.
 #[derive(Debug, Snafu)]
 pub enum EpubExtractionError {
     #[snafu(display("Failed to open epub as zip archive."))]
diff --git a/src/extractors/extractor.rs b/src/extractors/extractor.rs
index 3a582b3..511751f 100644
--- a/src/extractors/extractor.rs
+++ b/src/extractors/extractor.rs
@@ -7,6 +7,7 @@ use super::{
     pdf::{Pdf, PdfExtractionError},
 };
 
+/// Errors that occur during text extraction from documents.
 #[derive(Debug, Snafu)]
 pub enum ExtractionError {
     #[snafu(display("Failed to read input for extraction."))]
@@ -17,10 +18,13 @@ pub enum ExtractionError {
     Epub { source: EpubExtractionError },
 }
 
+/// Extract text content from document bytes.
 pub trait Extractor {
+    /// Extract text from document bytes.
     fn extract(input: &[u8]) -> Result<String, ExtractionError>;
 }
 
+/// Get file extension from path as lowercase string.
 pub fn extension<P: AsRef<Path>>(path: P) -> String {
     let path = path.as_ref();
     path.extension()
@@ -29,6 +33,7 @@ pub fn extension<P: AsRef<Path>>(path: P) -> String {
         .into_owned()
 }
 
+/// Extract text from input stream based on file extension.
 pub fn extract<R: Read>(mut input: R, extension: &str) -> Result<Option<String>, ExtractionError> {
     let mut buffer = Vec::new();
     input.read_to_end(&mut buffer).context(ReadSnafu)?;
diff --git a/src/extractors/pdf.rs b/src/extractors/pdf.rs
index a3b36b3..48b8695 100644
--- a/src/extractors/pdf.rs
+++ b/src/extractors/pdf.rs
@@ -3,8 +3,10 @@ use snafu::{ResultExt, Snafu};
 
 use super::extractor::{Extractor, PdfSnafu};
 
+/// PDF text extractor.
 pub struct Pdf;
 
+/// Extract text from all pages of a PDF document.
 fn get_pdf_text(doc: &Document) -> Result<String, lopdf::Error> {
     let pages: Vec<u32> = doc.get_pages().keys().cloned().collect();
     let text = doc.extract_text(&pages)?;
@@ -12,6 +14,7 @@ fn get_pdf_text(doc: &Document) -> Result<String, lopdf::Error> {
     Ok(text)
 }
 
+/// Errors that occur during PDF text extraction.
 #[derive(Debug, Snafu)]
 pub enum PdfExtractionError {
     #[snafu(display("Failed to open pdf."))]
diff --git a/src/storage/jobs.rs b/src/storage/jobs.rs
index 94942d8..5b8971c 100644
--- a/src/storage/jobs.rs
+++ b/src/storage/jobs.rs
@@ -7,12 +7,14 @@ use uuid::Uuid;
 
 use super::queries::DocumentMatch;
 
+/// Database operations for background job management.
 #[derive(Debug, Clone)]
 pub struct Jobs {
     /// Connection pool for database operations.
     pool: Arc<PgPool>,
 }
 
+/// Status of a background job.
 #[derive(Debug, Clone, Serialize, Deserialize, Type)]
 #[sqlx(type_name = "job_status", rename_all = "lowercase")]
 pub enum JobStatus {
@@ -75,6 +77,7 @@ pub enum RetrieveError {
 }
 
 impl Jobs {
+    /// Create a new jobs handler with database pool.
     pub fn new(pool: Arc<PgPool>) -> Self {
         Self { pool }
     }
@@ -114,6 +117,7 @@ impl Jobs {
         Ok(())
     }
 
+    /// Retrieve job status and results by ID.
     pub async fn retrieve(
         &self,
         id: &Uuid,
diff --git a/src/storage/queries.rs b/src/storage/queries.rs
index 65c8bc8..be988d2 100644
--- a/src/storage/queries.rs
+++ b/src/storage/queries.rs
@@ -7,6 +7,7 @@ use sqlx::{FromRow, PgPool};
 
 use crate::{hash::SHA256_LENGTH, text_encoder::Embeddings};
 
+/// Database operations for document queries and embeddings.
 #[derive(Debug, Clone)]
 pub struct Queries {
     /// Connection pool for database operations.
@@ -67,6 +68,7 @@ pub struct DocumentMatch {
 }
 
 impl Queries {
+    /// Create a new queries handler with database pool.
     pub fn new(pool: Arc<PgPool>) -> Self {
         Self { pool }
     }